diff --git a/epan/dfilter/grammar.lemon b/epan/dfilter/grammar.lemon
index 3815587c57..d6caa0d927 100644
--- a/epan/dfilter/grammar.lemon
+++ b/epan/dfilter/grammar.lemon
@@ -15,9 +15,6 @@
 
 #include "grammar.h"
 
-/* Generated lemon code warns on this. */
-DIAG_OFF(unreachable-code)
-
 #ifdef _WIN32
 #pragma warning(disable:4671)
 #endif
@@ -27,7 +24,11 @@ new_function(dfwork_t *dfw, stnode_t *node);
 
 #define FAIL(dfw, node, ...) dfilter_fail(dfw, stnode_location(node), __VA_ARGS__)
 
-/* End of C code */
+DIAG_OFF_LEMON()
+} /* end of %include */
+
+%code {
+DIAG_ON_LEMON()
 }
 
 /* Parser Information */
diff --git a/epan/dfilter/scanner.l b/epan/dfilter/scanner.l
index e1d428c032..b90f1a28b3 100644
--- a/epan/dfilter/scanner.l
+++ b/epan/dfilter/scanner.l
@@ -75,7 +75,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 stnode_t *df_lval;
 
@@ -475,7 +475,7 @@ hyphen-bytes	{hex2}(-{hex2})+
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 static void
 _update_location(df_scanner_state_t *state, size_t len)
diff --git a/epan/diam_dict.l b/epan/diam_dict.l
index afb5edb002..8506ade177 100644
--- a/epan/diam_dict.l
+++ b/epan/diam_dict.l
@@ -104,7 +104,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 typedef struct entity_t {
 	char* name;
@@ -630,7 +630,7 @@ description_attr description=\042
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 static int debugging  = 0;
 
diff --git a/epan/dtd_grammar.lemon b/epan/dtd_grammar.lemon
index 58f9c7ff0c..253da126cb 100644
--- a/epan/dtd_grammar.lemon
+++ b/epan/dtd_grammar.lemon
@@ -22,9 +22,6 @@
 #include "dtd.h"
 #include "dtd_parse.h"
 
-/* Generated lemon code warns on this. */
-DIAG_OFF(unreachable-code)
-
 static dtd_named_list_t* dtd_named_list_new(gchar* name, GPtrArray* list) {
 	dtd_named_list_t* nl = g_new(dtd_named_list_t,1);
 
@@ -45,6 +42,11 @@ static GPtrArray* g_ptr_array_join(GPtrArray* a, GPtrArray* b){
 	return a;
 }
 
+DIAG_OFF_LEMON()
+} /* end of %include */
+
+%code {
+DIAG_ON_LEMON()
 }
 
 %name DtdParse
diff --git a/epan/dtd_parse.l b/epan/dtd_parse.l
index f8da374c44..9d7677d8bf 100644
--- a/epan/dtd_parse.l
+++ b/epan/dtd_parse.l
@@ -92,7 +92,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 	struct _proto_xmlpi_attr {
 		const gchar* name;
@@ -353,7 +353,7 @@ squoted        ['][^\']*[']
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 static dtd_token_data_t* new_token(gchar* text, gchar* location) {
 	dtd_token_data_t* t = g_new(dtd_token_data_t,1);
diff --git a/epan/dtd_preparse.l b/epan/dtd_preparse.l
index 5a01c6977a..ff8ab141c1 100644
--- a/epan/dtd_preparse.l
+++ b/epan/dtd_preparse.l
@@ -101,7 +101,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 #define ECHO g_string_append(yyextra->current,yytext);
 
@@ -213,7 +213,7 @@ newline    \n
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 static const gchar* replace_entity(Dtd_PreParse_scanner_state_t* state, gchar* entity) {
 	GString* replacement;
diff --git a/epan/protobuf_lang_parser.lemon b/epan/protobuf_lang_parser.lemon
index 11034febff..820b99f340 100644
--- a/epan/protobuf_lang_parser.lemon
+++ b/epan/protobuf_lang_parser.lemon
@@ -30,9 +30,6 @@
 #include "protobuf_lang_parser.h"
 #include "protobuf_lang_scanner_lex.h"
 
-/* Generated lemon code warns on this. */
-DIAG_OFF(unreachable-code)
-
 #define NAME_TO_BE_SET "<NAME_TO_BE_SET>"
 #define NEED_NOT_NAME "<NEED_NOT_NAME>"
 
@@ -51,8 +48,13 @@ void pbl_parser_error(protobuf_lang_state_t *state, const char *fmt, ...);
    pbl_set_node_name() later. */
 #define CUR_LINENO (protobuf_lang_get_lineno(state->scanner))
 
+DIAG_OFF_LEMON()
 } /* end of %include */
 
+%code {
+DIAG_ON_LEMON()
+}
+
 %name ProtobufLangParser
 
 %extra_argument { protobuf_lang_state_t *state }
diff --git a/epan/protobuf_lang_scanner.l b/epan/protobuf_lang_scanner.l
index 187ba06839..335d960397 100644
--- a/epan/protobuf_lang_scanner.l
+++ b/epan/protobuf_lang_scanner.l
@@ -64,7 +64,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 /*
  * Sleazy hack to suppress compiler warnings in yy_fatal_error().
@@ -191,4 +191,4 @@ strdup_and_store(void* yyscanner, const char* text) {
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
diff --git a/epan/radius_dict.l b/epan/radius_dict.l
index 97a0d3aa50..c8c1825c13 100644
--- a/epan/radius_dict.l
+++ b/epan/radius_dict.l
@@ -96,7 +96,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 /*
  * See
@@ -413,7 +413,7 @@ static void add_value(Radius_scanner_state_t* state, const gchar* attrib_name, c
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 static void add_vendor(Radius_scanner_state_t* state, const gchar* name, guint32 id, guint type_octets, guint length_octets, gboolean has_flags) {
 	radius_vendor_info_t* v;
diff --git a/epan/uat_load.l b/epan/uat_load.l
index c9d0bcfe5e..06ab49ee23 100644
--- a/epan/uat_load.l
+++ b/epan/uat_load.l
@@ -98,7 +98,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 typedef struct {
 	uat_t* uat;
@@ -391,7 +391,7 @@ comment #[^\n]*\n
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 gboolean
 uat_load(uat_t *uat, const gchar *filename, char **errx)
diff --git a/include/ws_diag_control.h b/include/ws_diag_control.h
index a1ca422694..c4f7500633 100644
--- a/include/ws_diag_control.h
+++ b/include/ws_diag_control.h
@@ -164,7 +164,7 @@ extern "C" {
    *   warning C6387: 'XXX' could be '0'
    *   warning C28182: Dereferencing NULL pointer
    */
-  #define DIAG_OFF_FLEX \
+  #define DIAG_OFF_FLEX() \
     __pragma(warning(push)) \
     __pragma(warning(disable:4018)) \
     __pragma(warning(disable:4244)) \
@@ -174,7 +174,8 @@ extern "C" {
     __pragma(warning(disable:6386)) \
     __pragma(warning(disable:6387)) \
     __pragma(warning(disable:28182))
-  #define DIAG_ON_FLEX	__pragma(warning(pop))
+  #define DIAG_ON_FLEX() \
+    __pragma(warning(pop))
 #else
   /*
    * Suppress:
@@ -198,24 +199,35 @@ extern "C" {
    * you know what you're doing" warning that MSVC does?)
    */
   #if defined(__clang__) || defined(__APPLE__)
-    #define DIAG_OFF_FLEX \
+    #define DIAG_OFF_FLEX() \
       DIAG_OFF(sign-compare) \
       DIAG_OFF(shorten-64-to-32) \
       DIAG_OFF(unreachable-code) \
       DIAG_OFF(documentation)
-    #define DIAG_ON_FLEX \
+    #define DIAG_ON_FLEX() \
       DIAG_ON(documentation)    \
       DIAG_ON(unreachable-code) \
       DIAG_ON(shorten-64-to-32) \
       DIAG_ON(sign-compare)
   #else
-    #define DIAG_OFF_FLEX \
+    #define DIAG_OFF_FLEX() \
       DIAG_OFF(sign-compare)
-    #define DIAG_ON_FLEX \
+    #define DIAG_ON_FLEX() \
       DIAG_ON(sign-compare)
   #endif
 #endif
 
+/* Disable Lemon warnings. */
+#if defined(_MSC_VER)
+  #define DIAG_OFF_LEMON()
+  #define DIAG_ON_LEMON()
+#else
+  #define DIAG_OFF_LEMON() \
+    DIAG_OFF_CLANG(unreachable-code)
+  #define DIAG_ON_LEMON() \
+    DIAG_ON_CLANG(unreachable-code)
+#endif
+
 /*
  * Suppress warnings about casting away constness.
  * Do this only if you know that the pointer is to something that can
diff --git a/plugins/epan/mate/mate_grammar.lemon b/plugins/epan/mate/mate_grammar.lemon
index 802c6b8dab..be66915928 100644
--- a/plugins/epan/mate/mate_grammar.lemon
+++ b/plugins/epan/mate/mate_grammar.lemon
@@ -26,9 +26,6 @@
 #include <wsutil/file_util.h>
 #include <wsutil/str_util.h>
 
-/* Generated lemon code warns on this. */
-DIAG_OFF(unreachable-code)
-
 #define DUMMY void*
 
 typedef struct _extraction {
@@ -171,6 +168,11 @@ static gchar* recolonize(mate_config* mc, gchar* s) {
 	return r;
 }
 
+DIAG_OFF_LEMON()
+} /* end of %include */
+
+%code {
+DIAG_ON_LEMON()
 }
 
 %name MateParser
diff --git a/plugins/epan/mate/mate_parser.l b/plugins/epan/mate/mate_parser.l
index ad08c9ea7a..6e423abccd 100644
--- a/plugins/epan/mate/mate_parser.l
+++ b/plugins/epan/mate/mate_parser.l
@@ -87,7 +87,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 	void MateParseTrace(FILE*,char*);
 
@@ -337,7 +337,7 @@ blk_cmnt_stop  "*/"
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 static void ptr_array_free(gpointer data, gpointer user_data _U_)
 {
diff --git a/plugins/epan/wimaxasncp/wimaxasncp_dict.l b/plugins/epan/wimaxasncp/wimaxasncp_dict.l
index 3b42207e5e..05fa2e51eb 100644
--- a/plugins/epan/wimaxasncp/wimaxasncp_dict.l
+++ b/plugins/epan/wimaxasncp/wimaxasncp_dict.l
@@ -104,7 +104,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 typedef struct entity_t {
 	gchar *name;
@@ -517,7 +517,7 @@ since_attr since=\042
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 static int debugging  = 0;
 
diff --git a/ui/text_import_scanner.l b/ui/text_import_scanner.l
index 3918252a37..5dd466cb10 100644
--- a/ui/text_import_scanner.l
+++ b/ui/text_import_scanner.l
@@ -76,7 +76,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 /*
  * Flex (v 2.5.35) uses this symbol to "exclude" unistd.h
@@ -132,7 +132,7 @@ eol \r?\n\r?
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 import_status_t
 text_import_scan(FILE *input_file)
diff --git a/wiretap/ascend_parser.lemon b/wiretap/ascend_parser.lemon
index f9192f210a..89df92680f 100644
--- a/wiretap/ascend_parser.lemon
+++ b/wiretap/ascend_parser.lemon
@@ -140,10 +140,12 @@ static void AscendParserFree(void *p, void (*freeProc)(void*));
 #define ascend_debug(...)
 #endif
 
-/* Generated lemon code warns on this. */
-DIAG_OFF(unreachable-code)
+DIAG_OFF_LEMON()
+} /* end of %include */
 
-} // %include
+%code {
+DIAG_ON_LEMON()
+}
 
 %name AscendParser
 
diff --git a/wiretap/ascend_scanner.l b/wiretap/ascend_scanner.l
index 9b42fcf8e3..f6fe4032f0 100644
--- a/wiretap/ascend_scanner.l
+++ b/wiretap/ascend_scanner.l
@@ -64,7 +64,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 static int ascend_yyinput(void *buf, ascend_state_t *parser_state) {
     int c = file_getc(parser_state->fh);
@@ -406,4 +406,4 @@ task:|task|at|time:|octets { return KEYWORD; }
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
diff --git a/wiretap/busmaster_parser.lemon b/wiretap/busmaster_parser.lemon
index 3e346bfb7a..ce62aada88 100644
--- a/wiretap/busmaster_parser.lemon
+++ b/wiretap/busmaster_parser.lemon
@@ -34,8 +34,11 @@ static void merge_msg_data(msg_data_t *dst, const msg_data_t *a, const msg_data_
     memcpy(&dst->data[a->length], &b->data[0], b->length);
 }
 
-DIAG_OFF(unreachable-code)
+DIAG_OFF_LEMON()
+} /* end of %include */
 
+%code {
+DIAG_ON_LEMON()
 }
 
 %name BusmasterParser
@@ -369,8 +372,6 @@ data64(R) ::= data32(A) data32(B) . { merge_msg_data(&R, &A, &B); }
 
 %code {
 
-DIAG_ON(unreachable-code)
-
 #include "busmaster_scanner_lex.h"
 #include "busmaster_parser.h"
 
diff --git a/wiretap/busmaster_scanner.l b/wiretap/busmaster_scanner.l
index 419b9b3b92..eeaa88f563 100644
--- a/wiretap/busmaster_scanner.l
+++ b/wiretap/busmaster_scanner.l
@@ -86,7 +86,7 @@ static int busmaster_yyinput(void *buf, unsigned int length, busmaster_state_t *
 #define busmaster_realloc(ptr, size, yyscanner)   (void *)realloc((char *)(ptr), (size))
 #define busmaster_free(ptr, yyscanner)            free((char *)(ptr))
 
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 %}
 
@@ -196,4 +196,4 @@ NUM (0x)?[0-9A-Fa-f]+
 
 %%
 
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
diff --git a/wiretap/candump_parser.lemon b/wiretap/candump_parser.lemon
index 3fd659cc05..149c3a7dfa 100644
--- a/wiretap/candump_parser.lemon
+++ b/wiretap/candump_parser.lemon
@@ -34,8 +34,11 @@ static void merge_msg_data(msg_data_t *dst, const msg_data_t *a, const msg_data_
     memcpy(&dst->data[a->length], &b->data[0], b->length);
 }
 
-DIAG_OFF(unreachable-code)
+DIAG_OFF_LEMON()
+} /* end of %include */
 
+%code {
+DIAG_ON_LEMON()
 }
 
 %name CandumpParser
@@ -268,8 +271,6 @@ data64(R) ::= data32(A) data32(B) . { merge_msg_data(&R, &A, &B); }
 
 %code {
 
-DIAG_ON(unreachable-code)
-
 #include "candump_scanner_lex.h"
 #include "candump_parser.h"
 
diff --git a/wiretap/candump_scanner.l b/wiretap/candump_scanner.l
index bc1cdb38a2..c43c5349c2 100644
--- a/wiretap/candump_scanner.l
+++ b/wiretap/candump_scanner.l
@@ -89,7 +89,7 @@ static int candump_yyinput(void *buf, candump_state_t *state)
 #define candump_realloc(ptr, size, yyscanner)   (void *)realloc((char *)(ptr), (size))
 #define candump_free(ptr, yyscanner)            free((char *)(ptr))
 
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 %}
 
@@ -141,4 +141,4 @@ R                       {
 
 %%
 
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
diff --git a/wiretap/k12text.l b/wiretap/k12text.l
index 0bf009161c..d996db12cd 100644
--- a/wiretap/k12text.l
+++ b/wiretap/k12text.l
@@ -106,7 +106,7 @@
 /*
  * Disable diagnostics in the code generated by Flex.
  */
-DIAG_OFF_FLEX
+DIAG_OFF_FLEX()
 
 /*
  * State kept by the scanner.
@@ -245,7 +245,7 @@ hdlc HDLC
 /*
  * Turn diagnostics back on, so we check the code that we've written.
  */
-DIAG_ON_FLEX
+DIAG_ON_FLEX()
 
 /* Fill in pkthdr */