diff --git a/capinfos.c b/capinfos.c
index 96a7773e53..8accd470b7 100644
--- a/capinfos.c
+++ b/capinfos.c
@@ -1240,25 +1240,25 @@ process_cap_file(wtap *wth, const char *filename)
     wtap_optionblock_get_option_string(shb_inf, OPT_COMMENT, &shb_str);
     shb_str_no_newlines = g_strdup(shb_str);
     string_replace_newlines(shb_str_no_newlines);
-    wtap_optionblock_set_option_string(cf_info.shb, OPT_COMMENT, shb_str_no_newlines);
+    wtap_optionblock_set_option_string(cf_info.shb, OPT_COMMENT, shb_str_no_newlines, (gsize)(shb_str_no_newlines ? strlen(shb_str_no_newlines) : 0));
     g_free(shb_str_no_newlines);
 
     wtap_optionblock_get_option_string(shb_inf, OPT_SHB_HARDWARE, &shb_str);
     shb_str_no_newlines = g_strdup(shb_str);
     string_replace_newlines(shb_str_no_newlines);
-    wtap_optionblock_set_option_string(cf_info.shb, OPT_SHB_HARDWARE, shb_str_no_newlines);
+    wtap_optionblock_set_option_string(cf_info.shb, OPT_SHB_HARDWARE, shb_str_no_newlines, (gsize)(shb_str_no_newlines ? strlen(shb_str_no_newlines) : 0));
     g_free(shb_str_no_newlines);
 
     wtap_optionblock_get_option_string(shb_inf, OPT_SHB_OS, &shb_str);
     shb_str_no_newlines = g_strdup(shb_str);
     string_replace_newlines(shb_str_no_newlines);
-    wtap_optionblock_set_option_string(cf_info.shb, OPT_SHB_OS, shb_str_no_newlines);
+    wtap_optionblock_set_option_string(cf_info.shb, OPT_SHB_OS, shb_str_no_newlines, (gsize)(shb_str_no_newlines ? strlen(shb_str_no_newlines) : 0));
     g_free(shb_str_no_newlines);
 
     wtap_optionblock_get_option_string(shb_inf, OPT_SHB_USERAPPL, &shb_str);
     shb_str_no_newlines = g_strdup(shb_str);
     string_replace_newlines(shb_str_no_newlines);
-    wtap_optionblock_set_option_string(cf_info.shb, OPT_SHB_USERAPPL, shb_str_no_newlines);
+    wtap_optionblock_set_option_string(cf_info.shb, OPT_SHB_USERAPPL, shb_str_no_newlines, (gsize)(shb_str_no_newlines ? strlen(shb_str_no_newlines) : 0));
     g_free(shb_str_no_newlines);
   }
 
diff --git a/debian/libwiretap0.symbols b/debian/libwiretap0.symbols
index 2c7ff4a8d0..ec7bb30b9e 100644
--- a/debian/libwiretap0.symbols
+++ b/debian/libwiretap0.symbols
@@ -86,6 +86,7 @@ libwiretap.so.0 libwiretap0 #MINVER#
  wtap_optionblock_get_option_uint64@Base 2.1.0
  wtap_optionblock_set_option_custom@Base 2.1.0
  wtap_optionblock_set_option_string@Base 2.1.0
+ wtap_optionblock_set_option_string_format@Base 2.1.0
  wtap_optionblock_set_option_uint8@Base 2.1.0
  wtap_optionblock_set_option_uint64@Base 2.1.0
  wtap_pcap_encap_to_wtap_encap@Base 1.9.1
diff --git a/editcap.c b/editcap.c
index 0bcab3308c..a67e6ae747 100644
--- a/editcap.c
+++ b/editcap.c
@@ -1382,9 +1382,7 @@ main(int argc, char *argv[])
                 /* If we don't have an application name add Editcap */
                 wtap_optionblock_get_option_string(shb_hdr, OPT_SHB_USERAPPL, &shb_user_appl);
                 if (shb_user_appl == NULL) {
-                    shb_user_appl = g_strdup("Editcap " VERSION);
-                    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, shb_user_appl);
-                    g_free(shb_user_appl);
+                    wtap_optionblock_set_option_string_format(shb_hdr, OPT_SHB_USERAPPL, "Editcap " VERSION);
                 }
 
                 pdh = editcap_dump_open(filename,
diff --git a/epan/wslua/wslua.h b/epan/wslua/wslua.h
index fb067a2f38..8e074eb00c 100644
--- a/epan/wslua/wslua.h
+++ b/epan/wslua/wslua.h
@@ -618,7 +618,8 @@ extern int wslua_set__index(lua_State *L);
         } else { \
             return luaL_error(L, "%s's attribute `%s' must be a string or nil", #C , #field ); \
         } \
-        wtap_optionblock_set_option_string(obj->member, option, s); \
+        wtap_optionblock_set_option_string(obj->member, option, s, strlen(s)); \
+        g_free(s); \
         return 0; \
     } \
     /* silly little trick so we can add a semicolon after this macro */ \
diff --git a/tshark.c b/tshark.c
index c4ade31a2b..dc28f8769e 100644
--- a/tshark.c
+++ b/tshark.c
@@ -3272,9 +3272,7 @@ load_cap_file(capture_file *cf, char *save_file, int out_file_type,
     wtap_optionblock_get_option_string(shb_hdr, OPT_SHB_USERAPPL, &shb_user_appl);
     if (shb_user_appl == NULL) {
         /* this is free'd by wtap_optionblock_free() later */
-        shb_user_appl = g_strdup_printf("TShark (Wireshark) %s", get_ws_vcs_version_info());
-        wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, shb_user_appl);
-        g_free(shb_user_appl);
+        wtap_optionblock_set_option_string_format(shb_hdr, OPT_SHB_USERAPPL, "TShark (Wireshark) %s", get_ws_vcs_version_info());
     }
 
     if (linktype != WTAP_ENCAP_PER_PACKET &&
diff --git a/ui/gtk/file_import_dlg.c b/ui/gtk/file_import_dlg.c
index 5a5816fd27..b39b38fa0a 100644
--- a/ui/gtk/file_import_dlg.c
+++ b/ui/gtk/file_import_dlg.c
@@ -463,7 +463,7 @@ file_import_open(text_import_info_t *info)
     wtap_optionblock_t           int_data;
     wtapng_if_descr_mandatory_t *int_data_mand;
     GString                     *os_info_str;
-    gchar                       *opt_comment, *wireshark_ver;
+    gsize                        opt_len;
 
     /* Create data for SHB  */
     os_info_str = g_string_new("");
@@ -472,22 +472,19 @@ file_import_open(text_import_info_t *info)
     shb_hdr = wtap_optionblock_create(WTAP_OPTION_BLOCK_NG_SECTION);
 
     /* options */
-    opt_comment = g_strdup_printf("File created by File->Import of file %s", info->import_text_filename);
-    wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, opt_comment);
-    g_free(opt_comment);
+    wtap_optionblock_set_option_string_format(shb_hdr, OPT_COMMENT, "File created by File->Import of file %s", info->import_text_filename);
 
     /*
      * UTF-8 string containing the name of the operating system used to create
      * this section.
      */
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE));
+    opt_len = os_info_str->len;
+    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE), opt_len);
     /*
      * UTF-8 string containing the name of the application used to create
      * this section.
      */
-    wireshark_ver = g_strdup_printf("Wireshark %s", get_ws_vcs_version_info());
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, wireshark_ver);
-    g_free(wireshark_ver);
+    wtap_optionblock_set_option_string_format(shb_hdr, OPT_SHB_USERAPPL, "Wireshark %s", get_ws_vcs_version_info());
 
     /* Create fake IDB info */
     idb_inf = g_new(wtapng_iface_descriptions_t,1);
@@ -500,7 +497,7 @@ file_import_open(text_import_info_t *info)
     int_data_mand->time_units_per_second = 1000000; /* default microsecond resolution */
     int_data_mand->link_type             = wtap_wtap_encap_to_pcap_encap(info->encapsulation);
     int_data_mand->snap_len              = WTAP_MAX_PACKET_SIZE;
-    wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, "Fake IF File->Import");
+    wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, "Fake IF File->Import", strlen("Fake IF File->Import"));
 
     g_array_append_val(idb_inf->interface_data, int_data);
 
diff --git a/ui/tap_export_pdu.c b/ui/tap_export_pdu.c
index 3131973ed2..37706ba718 100644
--- a/ui/tap_export_pdu.c
+++ b/ui/tap_export_pdu.c
@@ -107,7 +107,7 @@ exp_pdu_open(exp_pdu_t *exp_pdu_tap_data, int fd, char *comment)
     wtap_optionblock_t           int_data;
     wtapng_if_descr_mandatory_t *int_data_mand;
     GString                     *os_info_str;
-    gchar                       *opt_comment, *wireshark_ver;
+    gsize                        opt_len;
 
     /* Create data for SHB  */
     os_info_str = g_string_new("");
@@ -116,22 +116,20 @@ exp_pdu_open(exp_pdu_t *exp_pdu_tap_data, int fd, char *comment)
     shb_hdr = wtap_optionblock_create(WTAP_OPTION_BLOCK_NG_SECTION);
 
     /* options */
-    opt_comment = comment;
-    wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, opt_comment);
-    g_free(opt_comment);
+    wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, comment, strlen(comment));
+    g_free(comment);
 
     /*
      * UTF-8 string containing the name of the operating system used to create
      * this section.
      */
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE));
+    opt_len = os_info_str->len;
+    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE), opt_len);
     /*
      * UTF-8 string containing the name of the application used to create
      * this section.
      */
-    wireshark_ver = g_strdup_printf("Wireshark %s", get_ws_vcs_version_info());
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, wireshark_ver);
-    g_free(wireshark_ver);
+    wtap_optionblock_set_option_string_format(shb_hdr, OPT_SHB_USERAPPL, "Wireshark %s", get_ws_vcs_version_info());
 
     /* Create fake IDB info */
     idb_inf = g_new(wtapng_iface_descriptions_t,1);
@@ -145,7 +143,7 @@ exp_pdu_open(exp_pdu_t *exp_pdu_tap_data, int fd, char *comment)
     int_data_mand->link_type       = wtap_wtap_encap_to_pcap_encap(WTAP_ENCAP_WIRESHARK_UPPER_PDU);
     int_data_mand->snap_len        = WTAP_MAX_PACKET_SIZE;
 
-    wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, "Fake IF, PDU->Export");
+    wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, "Fake IF, PDU->Export", strlen("Fake IF, PDU->Export"));
     wtap_optionblock_set_option_uint8(int_data, OPT_IDB_TSRESOL, 9);
 
     g_array_append_val(idb_inf->interface_data, int_data);
diff --git a/wiretap/erf.c b/wiretap/erf.c
index beb0fdecea..5ca207ae47 100644
--- a/wiretap/erf.c
+++ b/wiretap/erf.c
@@ -951,7 +951,6 @@ int erf_populate_interfaces(wtap *wth)
   wtap_optionblock_t int_data;
   wtapng_if_descr_mandatory_t* int_data_mand;
   int i;
-  char* tmp;
 
   if (!wth)
     return -1;
@@ -983,12 +982,8 @@ int erf_populate_interfaces(wtap *wth)
     int_data_mand->num_stat_entries = 0;
     int_data_mand->interface_statistics = NULL;
 
-    tmp = g_strdup_printf("Port %c", 'A'+i);
-    wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, tmp);
-    g_free(tmp);
-    tmp = g_strdup_printf("ERF Interface Id %d (Port %c)", i, 'A'+i);
-    wtap_optionblock_set_option_string(int_data, OPT_IDB_DESCR, tmp);
-    g_free(tmp);
+    wtap_optionblock_set_option_string_format(int_data, OPT_IDB_NAME, "Port %c", 'A'+i);
+    wtap_optionblock_set_option_string_format(int_data, OPT_IDB_DESCR, "ERF Interface Id %d (Port %c)", i, 'A'+i);
 
     g_array_append_val(wth->interface_data, int_data);
   }
@@ -1072,7 +1067,7 @@ static struct erf_if_mapping* erf_find_interface_mapping(erf_t *erf_priv, guint6
   return (struct erf_if_mapping*) g_hash_table_lookup(erf_priv->if_map, &if_map_lookup);
 }
 
-static gchar* erf_interface_descr_strdup(guint64 host_id, guint8 source_id, guint8 if_num, const gchar *descr)
+static void erf_set_interface_descr(wtap_optionblock_t block, guint option_id, guint64 host_id, guint8 source_id, guint8 if_num, const gchar *descr)
 {
   /* Source XXX,*/
   char sourceid_buf[16];
@@ -1091,9 +1086,9 @@ static gchar* erf_interface_descr_strdup(guint64 host_id, guint8 source_id, guin
   }
 
   if (descr) {
-    return g_strdup_printf("%s (ERF%s%s Interface %d)", descr, hostid_buf, sourceid_buf, if_num);
+    wtap_optionblock_set_option_string_format(block, option_id, "%s (ERF%s%s Interface %d)", descr, hostid_buf, sourceid_buf, if_num);
   } else {
-    return g_strdup_printf("Port %c (ERF%s%s Interface %d)", 'A'+if_num, hostid_buf, sourceid_buf, if_num);
+    wtap_optionblock_set_option_string_format(block, option_id, "Port %c (ERF%s%s Interface %d)", 'A'+if_num, hostid_buf, sourceid_buf, if_num);
   }
 }
 
@@ -1105,7 +1100,6 @@ static int erf_update_implicit_host_id(erf_t *erf_priv, wtap *wth, guint64 impli
   GList* item = NULL;
   wtap_optionblock_t int_data;
   struct erf_if_mapping* if_map = NULL;
-  char* tmp;
   int i;
 
   if (!erf_priv)
@@ -1137,12 +1131,8 @@ static int erf_update_implicit_host_id(erf_t *erf_priv, wtap *wth, guint64 impli
         if (if_map->interfaces[i].if_index >= 0) {
           /* XXX: this is a pointer! */
           int_data = g_array_index(wth->interface_data, wtap_optionblock_t, if_map->interfaces[i].if_index);
-          tmp = erf_interface_descr_strdup(implicit_host_id, if_map->source_id, (guint8) i, if_map->interfaces[i].name);
-          wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, tmp);
-          g_free(tmp);
-          tmp = erf_interface_descr_strdup(implicit_host_id, if_map->source_id, (guint8) i, if_map->interfaces[i].descr);
-          wtap_optionblock_set_option_string(int_data, OPT_IDB_DESCR, tmp);
-          g_free(tmp);
+          erf_set_interface_descr(int_data, OPT_IDB_NAME, implicit_host_id, if_map->source_id, (guint8) i, if_map->interfaces[i].name);
+          erf_set_interface_descr(int_data, OPT_IDB_DESCR, implicit_host_id, if_map->source_id, (guint8) i, if_map->interfaces[i].descr);
         }
       }
       /* Re-add the item under the implicit Host ID */
@@ -1162,7 +1152,6 @@ int erf_populate_interface(erf_t *erf_priv, wtap *wth, union wtap_pseudo_header
   wtap_optionblock_t int_data;
   wtapng_if_descr_mandatory_t* int_data_mand;
   struct erf_if_mapping* if_map = NULL;
-  char* tmp;
 
   if (!wth || !pseudo_header || !erf_priv || if_num > 3)
     return -1;
@@ -1219,12 +1208,8 @@ int erf_populate_interface(erf_t *erf_priv, wtap *wth, union wtap_pseudo_header
   int_data_mand->num_stat_entries = 0;
   int_data_mand->interface_statistics = NULL;
 
-  tmp = erf_interface_descr_strdup(host_id, source_id, if_num, NULL);
-  wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, tmp);
-  g_free(tmp);
-  tmp = erf_interface_descr_strdup(host_id, source_id, if_num, NULL);
-  wtap_optionblock_set_option_string(int_data, OPT_IDB_DESCR, tmp);
-  g_free(tmp);
+  erf_set_interface_descr(int_data, OPT_IDB_NAME, host_id, source_id, if_num, NULL);
+  erf_set_interface_descr(int_data, OPT_IDB_DESCR, host_id, source_id, if_num, NULL);
 
   if_map->interfaces[if_num].if_index = (int) wth->interface_data->len;
   g_array_append_val(wth->interface_data, int_data);
@@ -1290,14 +1275,7 @@ static int populate_capture_host_info(erf_t *erf_priv, wtap *wth, union wtap_pse
 
         switch (tag.type) {
           case ERF_META_TAG_comment:
-            /*
-             * XXX: Would be really nice if wtap_optionblock_set_option_string()
-             * supported supplying a length (or didn't strdup), this is all
-             * through PCAP-NG too.
-             */
-            tmp = g_strndup((gchar*) tag.value, tag.length);
-            wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, tmp);
-            g_free(tmp);
+            wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, tag.value, tag.length);
             break;
         }
         /* Fall through */
@@ -1322,9 +1300,7 @@ static int populate_capture_host_info(erf_t *erf_priv, wtap *wth, union wtap_pse
             descr = g_strndup((gchar*) tag.value, tag.length);
             break;
           case ERF_META_TAG_os:
-            tmp = g_strndup((gchar*) tag.value, tag.length);
-            wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, tmp);
-            g_free(tmp);
+            wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, tag.value, tag.length);
             break;
           case ERF_META_TAG_app_name:
             g_free(app_name);
@@ -1353,7 +1329,7 @@ static int populate_capture_host_info(erf_t *erf_priv, wtap *wth, union wtap_pse
     /* If no app_version will just use app_name */
 
     tmp = g_strjoin(" ", app_name, app_version, NULL);
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, tmp);
+    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, tmp, strlen(tmp));
     g_free(tmp);
 
     g_free(app_name);
@@ -1382,15 +1358,13 @@ static int populate_capture_host_info(erf_t *erf_priv, wtap *wth, union wtap_pse
   /* Combine into "Description (Model; CPU)" */
   if (state->sectiontype == ERF_META_SECTION_HOST && descr) {
     if (modelcpu) {
-      tmp = g_strdup_printf("%s (%s)", descr, modelcpu);
-      wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_HARDWARE, tmp);
-      g_free(tmp);
+      wtap_optionblock_set_option_string_format(shb_hdr, OPT_SHB_HARDWARE, "%s (%s)", descr, modelcpu);
     } else {
-      wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_HARDWARE, descr);
+      wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_HARDWARE, descr, strlen(descr));
       /*descr = NULL;*/
     }
-  } else {
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_HARDWARE, modelcpu);
+  } else if (modelcpu) {
+    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_HARDWARE, modelcpu, strlen(modelcpu));
     /*modelcpu = NULL;*/
   }
 
@@ -1458,7 +1432,6 @@ static int populate_interface_info(erf_t *erf_priv, wtap *wth, union wtap_pseudo
   wtap_optionblock_t int_data = NULL;
   wtapng_if_descr_mandatory_t* int_data_mand = NULL;
   wtapng_if_descr_filter_t if_filter;
-  char* tmp;
   guint32 if_num = 0;
   struct erf_if_info* if_info = NULL;
 
@@ -1539,30 +1512,22 @@ static int populate_interface_info(erf_t *erf_priv, wtap *wth, union wtap_pseudo
         /* TODO: fall back to module "dev_name Port N"? */
         if (!if_info->name) {
           if_info->name = g_strndup((gchar*) tag.value, tag.length);
-          tmp = erf_interface_descr_strdup(state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->name);
-          wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, tmp);
-          g_free(tmp);
+          erf_set_interface_descr(int_data, OPT_IDB_NAME, state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->name);
 
           /* If we have no description, also copy to wtap if_description */
           if (!if_info->descr) {
-            tmp = erf_interface_descr_strdup(state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->name);
-            wtap_optionblock_set_option_string(int_data, OPT_IDB_DESCR, tmp);
-            g_free(tmp);
+            erf_set_interface_descr(int_data, OPT_IDB_DESCR, state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->name);
           }
         }
         break;
       case ERF_META_TAG_descr:
         if (!if_info->descr) {
           if_info->descr = g_strndup((gchar*) tag.value, tag.length);
-          tmp = erf_interface_descr_strdup(state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->descr);
-          wtap_optionblock_set_option_string(int_data, OPT_IDB_DESCR, tmp);
-          g_free(tmp);
+          erf_set_interface_descr(int_data, OPT_IDB_DESCR, state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->descr);
 
           /* If we have no name, also copy to wtap if_name */
           if (!if_info->name) {
-            tmp = erf_interface_descr_strdup(state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->descr);
-            wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, tmp);
-            g_free(tmp);
+            erf_set_interface_descr(int_data, OPT_IDB_NAME, state->if_map->host_id, state->if_map->source_id, (guint8) if_num, if_info->descr);
           }
         }
         break;
@@ -1592,9 +1557,7 @@ static int populate_interface_info(erf_t *erf_priv, wtap *wth, union wtap_pseudo
         }
         break;
       case ERF_META_TAG_comment:
-        tmp = g_strndup((gchar*) tag.value, tag.length);
-        wtap_optionblock_set_option_string(int_data, OPT_COMMENT, tmp);
-        g_free(tmp);
+        wtap_optionblock_set_option_string(int_data, OPT_COMMENT, tag.value, tag.length);
         break;
       case ERF_META_TAG_filter:
         if_filter.if_filter_str = g_strndup((gchar*) tag.value, tag.length);
diff --git a/wiretap/file_access.c b/wiretap/file_access.c
index 61653fc311..0f5dbd52c0 100644
--- a/wiretap/file_access.c
+++ b/wiretap/file_access.c
@@ -2204,7 +2204,8 @@ wtap_dump_init_dumper(int file_type_subtype, int encap, int snaplen, gboolean co
 		descr_mand->time_units_per_second = 1000000; /* default microsecond resolution */
 		descr_mand->link_type = wtap_wtap_encap_to_pcap_encap(encap);
 		descr_mand->snap_len = snaplen;
-		wtap_optionblock_set_option_string(descr, OPT_IDB_NAME, "Unknown/not available in original file format(libpcap)");
+		wtap_optionblock_set_option_string(descr, OPT_IDB_NAME, "Unknown/not available in original file format(libpcap)",
+														strlen("Unknown/not available in original file format(libpcap)"));
 
 		descr_mand->num_stat_entries = 0;          /* Number of ISB:s */
 		descr_mand->interface_statistics = NULL;
diff --git a/wiretap/lanalyzer.c b/wiretap/lanalyzer.c
index 72ebba82e3..eb4ad3815e 100644
--- a/wiretap/lanalyzer.c
+++ b/wiretap/lanalyzer.c
@@ -323,12 +323,15 @@ wtap_open_return_val lanalyzer_open(wtap *wth, int *err, gchar **err_info)
             comment = (char *)g_malloc(record_length + 1);
             if (!wtap_read_bytes(wth->fh, comment, record_length,
                                  err, err_info)) {
-                  if (*err != WTAP_ERR_SHORT_READ)
-                        return WTAP_OPEN_ERROR;
+                  if (*err != WTAP_ERR_SHORT_READ) {
+                      g_free(comment);
+                      return WTAP_OPEN_ERROR;
+                  }
+                  g_free(comment);
                   return WTAP_OPEN_NOT_MINE;
             }
-            comment[record_length] = '\0';
-            wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, comment);
+            wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, comment, record_length);
+            g_free(comment);
       }
 
       /* If we made it this far, then the file is a LANAlyzer file.
diff --git a/wiretap/merge.c b/wiretap/merge.c
index 83ad2f35e6..52709c8948 100644
--- a/wiretap/merge.c
+++ b/wiretap/merge.c
@@ -370,6 +370,7 @@ create_shb_header(const merge_in_file_t *in_files, const guint in_file_count,
     guint i;
     char* shb_comment = NULL;
     wtapng_mandatory_section_t* shb_data;
+    gsize opt_len;
 
     shb_hdr = wtap_file_get_shb_for_new_file(in_files[0].wth);
 
@@ -396,13 +397,15 @@ create_shb_header(const merge_in_file_t *in_files, const guint in_file_count,
     shb_data = (wtapng_mandatory_section_t*)wtap_optionblock_get_mandatory_data(shb_hdr);
     shb_data->section_length = -1;
     /* TODO: handle comments from each file being merged */
-    wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, g_string_free(comment_gstr, TRUE)); /* section comment */
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_HARDWARE, NULL ); /* NULL if not available, UTF-8 string containing the        */
+    opt_len = comment_gstr->len;
+    wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, g_string_free(comment_gstr, TRUE), opt_len); /* section comment */
+    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_HARDWARE, NULL, 0 ); /* NULL if not available, UTF-8 string containing the        */
                                                                                       /*  description of the hardware used to create this section. */
 
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE)); /* UTF-8 string containing the name   */
+    opt_len = os_info_str->len;
+    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE), opt_len); /* UTF-8 string containing the name   */
                                                                                                             /*  of the operating system used to create this section.     */
-    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, (char*)app_name ); /* NULL if not available, UTF-8 string containing the name */
+    wtap_optionblock_set_option_string(shb_hdr, OPT_SHB_USERAPPL, (char*)app_name, app_name ? strlen(app_name): 0 ); /* NULL if not available, UTF-8 string containing the name */
                                                                                       /*  of the application used to create this section.          */
 
     return shb_hdr;
diff --git a/wiretap/nettrace_3gpp_32_423.c b/wiretap/nettrace_3gpp_32_423.c
index a93ff1d9ac..9fd47fbc1d 100644
--- a/wiretap/nettrace_3gpp_32_423.c
+++ b/wiretap/nettrace_3gpp_32_423.c
@@ -214,10 +214,10 @@ nettrace_close(wtap *wth)
 	wtap_close(file_info->wth_tmp_file);
 
 	/*Clear the shb info, it's been freed by wtap_close*/
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, NULL);
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_HARDWARE, NULL);
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_OS, NULL);
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_USERAPPL, NULL);
+	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, NULL, 0);
+	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_HARDWARE, NULL, 0);
+	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_OS, NULL, 0);
+	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_USERAPPL, NULL, 0);
 
 	/* delete the temp file */
 	ws_unlink(file_info->tmpname);
@@ -730,10 +730,10 @@ create_temp_pcapng_file(wtap *wth, int *err, gchar **err_info, nettrace_3gpp_32_
 	int scan_found;
 	unsigned second, ms;
 	gboolean do_random = FALSE;
-	gchar* wireshark_ver;
 	char *curr_pos, *next_msg_pos, *next_pos, *prev_pos;
 	int name_str_len;
 	char name_str[64];
+	gsize opt_len;
 	/* Info to build exported_pdu tags*/
 	exported_pdu_info_t  exported_pdu_info;
 
@@ -760,20 +760,20 @@ create_temp_pcapng_file(wtap *wth, int *err, gchar **err_info, nettrace_3gpp_32_
 
 	shb_hdr = wtap_optionblock_create(WTAP_OPTION_BLOCK_NG_SECTION);
 	/* options */
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, "File converted to Exported PDU format during opening");
+	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, "File converted to Exported PDU format during opening",
+															strlen("File converted to Exported PDU format during opening"));
 	/*
 	* UTF-8 string containing the name of the operating system used to create
 	* this section.
 	*/
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE));
+	opt_len = os_info_str->len;
+	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_OS, g_string_free(os_info_str, TRUE), opt_len);
 
 	/*
 	* UTF-8 string containing the name of the application used to create
 	* this section.
 	*/
-	wireshark_ver = g_strdup_printf("Wireshark %s", get_ws_vcs_version_info());
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_SHB_USERAPPL, wireshark_ver);
-	g_free(wireshark_ver);
+	wtap_optionblock_set_option_string_format(wth->shb_hdr, OPT_SHB_USERAPPL, "Wireshark %s", get_ws_vcs_version_info());
 
 	/* Create fake IDB info */
 	idb_inf = g_new(wtapng_iface_descriptions_t, 1);
@@ -786,7 +786,7 @@ create_temp_pcapng_file(wtap *wth, int *err, gchar **err_info, nettrace_3gpp_32_
 	int_data_mand->time_units_per_second = 1000000; /* default microsecond resolution */
 	int_data_mand->link_type = wtap_wtap_encap_to_pcap_encap(WTAP_ENCAP_WIRESHARK_UPPER_PDU);
 	int_data_mand->snap_len = WTAP_MAX_PACKET_SIZE;
-	wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, "Fake IF");
+	wtap_optionblock_set_option_string(int_data, OPT_IDB_NAME, "Fake IF", strlen("Fake IF"));
 	int_data_mand->num_stat_entries = 0;          /* Number of ISB:s */
 	int_data_mand->interface_statistics = NULL;
 
diff --git a/wiretap/pcapng.c b/wiretap/pcapng.c
index 3ebbfcaf1c..fa483367d1 100644
--- a/wiretap/pcapng.c
+++ b/wiretap/pcapng.c
@@ -620,7 +620,7 @@ pcapng_read_section_header_block(FILE_T fh, pcapng_block_header_t *bh,
             case(OPT_COMMENT):
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_section_header_block: opt_comment %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -630,7 +630,7 @@ pcapng_read_section_header_block(FILE_T fh, pcapng_block_header_t *bh,
             case(OPT_SHB_HARDWARE):
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_SHB_HARDWARE, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_SHB_HARDWARE, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_section_header_block: shb_hardware %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -640,7 +640,7 @@ pcapng_read_section_header_block(FILE_T fh, pcapng_block_header_t *bh,
             case(OPT_SHB_OS):
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_SHB_OS, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_SHB_OS, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_section_header_block: shb_os %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -650,7 +650,7 @@ pcapng_read_section_header_block(FILE_T fh, pcapng_block_header_t *bh,
             case(OPT_SHB_USERAPPL):
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_SHB_USERAPPL, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_SHB_USERAPPL, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_section_header_block: shb_user_appl %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -781,7 +781,7 @@ pcapng_read_if_descr_block(wtap *wth, FILE_T fh, pcapng_block_header_t *bh,
             case(OPT_COMMENT): /* opt_comment */
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_if_descr_block: opt_comment %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -791,7 +791,7 @@ pcapng_read_if_descr_block(wtap *wth, FILE_T fh, pcapng_block_header_t *bh,
             case(OPT_IDB_NAME): /* if_name */
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_IDB_NAME, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_IDB_NAME, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_if_descr_block: if_name %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -801,7 +801,7 @@ pcapng_read_if_descr_block(wtap *wth, FILE_T fh, pcapng_block_header_t *bh,
             case(OPT_IDB_DESCR): /* if_description */
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_IDB_DESCR, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_IDB_DESCR, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_if_descr_block: if_description %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -900,7 +900,7 @@ pcapng_read_if_descr_block(wtap *wth, FILE_T fh, pcapng_block_header_t *bh,
                  */
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_IDB_OS, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_IDB_OS, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_if_descr_block: if_os %s", tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -1847,7 +1847,7 @@ read_options:
             case(OPT_COMMENT):
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_name_resolution_block: length %u opt_comment '%s'", oh.option_length, tmp_content);
                     g_free(tmp_content);
                 } else {
@@ -1975,9 +1975,9 @@ pcapng_read_interface_statistics_block(FILE_T fh, pcapng_block_header_t *bh, pca
             case(OPT_COMMENT): /* opt_comment */
                 if (oh.option_length > 0 && oh.option_length < opt_cont_buf_len) {
                     tmp_content = g_strndup((char *)option_content, oh.option_length);
-                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, tmp_content);
-                    g_free(tmp_content);
+                    wtap_optionblock_set_option_string(wblock->block, OPT_COMMENT, option_content, oh.option_length);
                     pcapng_debug("pcapng_read_interface_statistics_block: opt_comment %s", tmp_content);
+                    g_free(tmp_content);
                 } else {
                     pcapng_debug("pcapng_read_interface_statistics_block: opt_comment length %u seems strange", oh.option_length);
                 }
diff --git a/wiretap/wtap.c b/wiretap/wtap.c
index 30f4123fe0..bdc74adcbf 100644
--- a/wiretap/wtap.c
+++ b/wiretap/wtap.c
@@ -191,7 +191,7 @@ wtap_file_get_shb_for_new_file(wtap *wth)
 
 	/* options */
 	wtap_optionblock_get_option_string(wth->shb_hdr, OPT_COMMENT, &opt_comment);
-	wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, opt_comment);
+	wtap_optionblock_set_option_string(shb_hdr, OPT_COMMENT, opt_comment, (gsize)(opt_comment ? strlen(opt_comment) : 0));
 
 	return shb_hdr;
 }
@@ -221,13 +221,13 @@ wtap_write_nrb_comment(wtap *wth, gchar *comment)
 		wth->nrb_hdr = wtap_optionblock_create(WTAP_OPTION_BLOCK_NG_NRB);
 	}
 
-	wtap_optionblock_set_option_string(wth->nrb_hdr, OPT_COMMENT, comment);
+	wtap_optionblock_set_option_string(wth->nrb_hdr, OPT_COMMENT, comment, (gsize)(comment ? strlen(comment) : 0));
 }
 
 void
 wtap_write_shb_comment(wtap *wth, gchar *comment)
 {
-	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, comment);
+	wtap_optionblock_set_option_string(wth->shb_hdr, OPT_COMMENT, comment, (gsize)(comment ? strlen(comment) : 0));
 }
 
 wtapng_iface_descriptions_t *
diff --git a/wiretap/wtap_opttypes.c b/wiretap/wtap_opttypes.c
index 7ae09a3669..9c53b48a9d 100644
--- a/wiretap/wtap_opttypes.c
+++ b/wiretap/wtap_opttypes.c
@@ -389,7 +389,7 @@ int wtap_optionblock_add_option(wtap_optionblock_t block, guint option_id, wtap_
     return WTAP_OPTTYPE_SUCCESS;
 }
 
-int wtap_optionblock_set_option_string(wtap_optionblock_t block, guint option_id, char* value)
+int wtap_optionblock_set_option_string(wtap_optionblock_t block, guint option_id, char* value, gsize value_length)
 {
     wtap_optblock_value_t* opt_value = wtap_optionblock_get_option(block, option_id);
 
@@ -401,7 +401,26 @@ int wtap_optionblock_set_option_string(wtap_optionblock_t block, guint option_id
         return WTAP_OPTTYPE_TYPE_MISMATCH;
 
     g_free(opt_value->option.stringval);
-    opt_value->option.stringval = g_strdup(value);
+    opt_value->option.stringval = g_strndup(value, value_length);
+    return WTAP_OPTTYPE_SUCCESS;
+}
+
+int wtap_optionblock_set_option_string_format(wtap_optionblock_t block, guint option_id, const char *format, ...)
+{
+    va_list va;
+    wtap_optblock_value_t* opt_value = wtap_optionblock_get_option(block, option_id);
+
+    /* Didn't find the option */
+    if (opt_value == NULL)
+        return WTAP_OPTTYPE_NOT_FOUND;
+
+    if (opt_value->info->type != WTAP_OPTTYPE_STRING)
+        return WTAP_OPTTYPE_TYPE_MISMATCH;
+
+    g_free(opt_value->option.stringval);
+    va_start(va, format);
+    opt_value->option.stringval = g_strdup_vprintf(format, va);
+    va_end(va);
     return WTAP_OPTTYPE_SUCCESS;
 }
 
diff --git a/wiretap/wtap_opttypes.h b/wiretap/wtap_opttypes.h
index 410dcb2e32..56d0c29e19 100644
--- a/wiretap/wtap_opttypes.h
+++ b/wiretap/wtap_opttypes.h
@@ -133,9 +133,20 @@ int wtap_optionblock_add_option(wtap_optionblock_t block, guint option_id, wtap_
  * @param[in] block Block to add option
  * @param[in] option_id Identifier value for option
  * @param[in] value New value of option
+ * @param[in] value_length Maximum length of string to copy.
  * @return 0 if successful
  */
-WS_DLL_PUBLIC int wtap_optionblock_set_option_string(wtap_optionblock_t block, guint option_id, char* value);
+WS_DLL_PUBLIC int wtap_optionblock_set_option_string(wtap_optionblock_t block, guint option_id, char* value, gsize value_length);
+
+/** Set printf-styled string option value to an option block
+ *
+ * @param[in] block Block to add option
+ * @param[in] option_id Identifier value for option
+ * @param[in] format printf like format string
+ * @return 0 if successful
+ */
+WS_DLL_PUBLIC int wtap_optionblock_set_option_string_format(wtap_optionblock_t block, guint option_id, const char *format, ...)
+                                                            G_GNUC_PRINTF(3,4);
 
 /** Get string option value from an option block
  *