diff --git a/epan/prefs-int.h b/epan/prefs-int.h
index e10cf3d61d..2a6dee279e 100644
--- a/epan/prefs-int.h
+++ b/epan/prefs-int.h
@@ -174,6 +174,21 @@ struct preference {
  */
 typedef prefs_set_pref_e (*pref_set_pair_cb) (gchar *key, const gchar *value, void *private_data, gboolean return_range_errors);
 
+/** Set the value of a string-like preference. */
+WS_DLL_PUBLIC
+void
+prefs_set_string_like_value(pref_t *pref, const gchar *value, gboolean *changed);
+
+/** Set the value of a range preference.  Return FALSE on error, TRUE otherwise. */
+WS_DLL_PUBLIC
+gboolean
+prefs_set_range_value(pref_t *pref, const gchar *value, gboolean *changed);
+
+/** Set the value of an enum preference. */
+WS_DLL_PUBLIC
+void
+prefs_set_enum_value(pref_t *pref, const gchar *value, gboolean *changed);
+
 /** read the preferences file (or similar) and call the callback
  * function to set each key/value pair found
  */
diff --git a/epan/prefs.c b/epan/prefs.c
index ec288b1864..c6e7b1e9a4 100644
--- a/epan/prefs.c
+++ b/epan/prefs.c
@@ -1022,6 +1022,23 @@ register_string_like_preference(module_t *module, const char *name,
     return preference;
 }
 
+/*
+ * For use by UI code that sets preferences.
+ */
+void
+prefs_set_string_like_value(pref_t *pref, const gchar *value, gboolean *changed)
+{
+    if (*pref->varp.string) {
+        if (strcmp(*pref->varp.string, value) != 0) {
+            *changed = TRUE;
+            g_free((void *)*pref->varp.string);
+            *pref->varp.string = g_strdup(value);
+        }
+    } else if (value) {
+        *pref->varp.string = g_strdup(value);
+    }
+}
+
 /*
  * Register a preference with a character-string value.
  */
@@ -1107,6 +1124,36 @@ prefs_register_range_preference(module_t *module, const char *name,
     preference->stashed_val.range = NULL;
 }
 
+static gboolean
+prefs_set_range_value_work(pref_t *pref, const gchar *value,
+                           gboolean return_range_errors, gboolean *changed)
+{
+    range_t *newrange;
+
+    if (range_convert_str_work(&newrange, value, pref->info.max_value,
+                               return_range_errors) != CVT_NO_ERROR) {
+        return FALSE;        /* number was bad */
+    }
+
+    if (!ranges_are_equal(*pref->varp.range, newrange)) {
+        *changed = TRUE;
+        g_free(*pref->varp.range);
+        *pref->varp.range = newrange;
+    } else {
+        g_free(newrange);
+    }
+    return TRUE;
+}
+
+/*
+ * For use by UI code that sets preferences.
+ */
+gboolean
+prefs_set_range_value(pref_t *pref, const gchar *value, gboolean *changed)
+{
+    return prefs_set_range_value_work(pref, value, TRUE, changed);
+}
+
 /*
  * Register a static text 'preference'.  It can be used to add explanatory
  * text inline with other preferences in the GUI.
@@ -1456,15 +1503,7 @@ column_hidden_set_cb(pref_t* pref, const gchar* value, gboolean* changed)
     fmt_data    *cfmt;
     pref_t  *format_pref;
 
-    if (*pref->varp.string) {
-        if (strcmp(*pref->varp.string, value) != 0) {
-            *changed = TRUE;
-            g_free((void *)*pref->varp.string);
-            *pref->varp.string = g_strdup(value);
-        }
-    } else if (value) {
-        *pref->varp.string = g_strdup(value);
-    }
+    prefs_set_string_like_value(pref, value, changed);
 
     /*
      * Set the "visible" flag for the existing columns; we need to
@@ -1995,11 +2034,7 @@ colorized_frame_reset_cb(pref_t* pref)
 static prefs_set_pref_e
 colorized_frame_set_cb(pref_t* pref, const gchar* value, gboolean* changed)
 {
-    if (strcmp(*pref->varp.string, value) != 0) {
-        *changed = TRUE;
-        g_free((void *)*pref->varp.string);
-        *pref->varp.string = g_strdup(value);
-    }
+    prefs_set_string_like_value(pref, value, changed);
 
     return PREFS_SET_OK;
 }
@@ -4394,29 +4429,14 @@ set_pref(gchar *pref_name, const gchar *value, void *private_data _U_,
         case PREF_STRING:
         case PREF_FILENAME:
         case PREF_DIRNAME:
-            if (strcmp(*pref->varp.string, value) != 0) {
-                module->prefs_changed = TRUE;
-                g_free((void *)*pref->varp.string);
-                *pref->varp.string = g_strdup(value);
-            }
+            prefs_set_string_like_value(pref, value, &module->prefs_changed);
             break;
 
         case PREF_RANGE:
         {
-            range_t *newrange;
-
-            if (range_convert_str_work(&newrange, value, pref->info.max_value,
-                                       return_range_errors) != CVT_NO_ERROR) {
+            if (!prefs_set_range_value_work(pref, value, return_range_errors,
+                                            &module->prefs_changed))
                 return PREFS_SET_SYNTAX_ERR;        /* number was bad */
-            }
-
-            if (!ranges_are_equal(*pref->varp.range, newrange)) {
-                module->prefs_changed = TRUE;
-                g_free(*pref->varp.range);
-                *pref->varp.range = newrange;
-            } else {
-                g_free (newrange);
-            }
             break;
         }
 
diff --git a/ui/gtk/main_menubar.c b/ui/gtk/main_menubar.c
index d8bccc9aff..f2b87383c2 100644
--- a/ui/gtk/main_menubar.c
+++ b/ui/gtk/main_menubar.c
@@ -4784,7 +4784,6 @@ menu_prefs_change_ok (GtkWidget *w, gpointer parent_w)
     module_t    *module    = (module_t *)g_object_get_data (G_OBJECT(w), "module");
     pref_t      *pref      = (pref_t *)g_object_get_data (G_OBJECT(w), "pref");
     const gchar *new_value = gtk_entry_get_text(GTK_ENTRY(entry));
-    range_t     *newrange;
     gchar       *p;
     guint        uval;
 
@@ -4803,26 +4802,15 @@ menu_prefs_change_ok (GtkWidget *w, gpointer parent_w)
         }
         break;
     case PREF_STRING:
-        if (strcmp (*pref->varp.string, new_value) != 0) {
-            module->prefs_changed = TRUE;
-            g_free((void*)*pref->varp.string);
-            *pref->varp.string = g_strdup(new_value);
-        }
+        prefs_set_string_like_value(pref, new_value, &module->prefs_changed);
         break;
     case PREF_RANGE:
-        if (range_convert_str(&newrange, new_value, pref->info.max_value) != CVT_NO_ERROR) {
+        if (!prefs_set_range_value(pref, new_value, &module->prefs_changed)) {
             simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK,
                           "The value \"%s\" isn't a valid range.",
                           new_value);
             return;
         }
-        if (!ranges_are_equal(*pref->varp.range, newrange)) {
-            module->prefs_changed = TRUE;
-            g_free(*pref->varp.range);
-            *pref->varp.range = newrange;
-        } else {
-            g_free (newrange);
-        }
         break;
     default:
         g_assert_not_reached();
diff --git a/ui/gtk/prefs_dlg.c b/ui/gtk/prefs_dlg.c
index 42f9fcae2f..ba5b94c7b0 100644
--- a/ui/gtk/prefs_dlg.c
+++ b/ui/gtk/prefs_dlg.c
@@ -1085,36 +1085,19 @@ pref_fetch(pref_t *pref, gpointer user_data)
   case PREF_FILENAME:
   case PREF_DIRNAME:
     str_val = gtk_entry_get_text(GTK_ENTRY(pref->control));
-    if (strcmp(*pref->varp.string, str_val) != 0) {
-      *pref_changed_p = TRUE;
-      g_free((void *)*pref->varp.string);
-      *pref->varp.string = g_strdup(str_val);
-    }
+    prefs_set_string_like_value(pref, str_val, pref_changed_p);
     break;
 
   case PREF_RANGE:
-  {
-    range_t *newrange;
-    convert_ret_t ret;
-
     str_val = gtk_entry_get_text(GTK_ENTRY(pref->control));
-    ret = range_convert_str(&newrange, str_val, pref->info.max_value);
-    if (ret != CVT_NO_ERROR)
+    if (!prefs_set_range_value(pref, str_val, pref_changed_p))
 #if 0
       return PREFS_SET_SYNTAX_ERR;      /* range was bad */
 #else
       return 0; /* XXX - should fail */
 #endif
 
-    if (!ranges_are_equal(*pref->varp.range, newrange)) {
-      *pref_changed_p = TRUE;
-      g_free(*pref->varp.range);
-      *pref->varp.range = newrange;
-    } else
-      g_free(newrange);
-
     break;
-  }
 
   case PREF_STATIC_TEXT:
   case PREF_UAT: