diff --git a/epan/dissectors/x11-extension-implementation.h b/epan/dissectors/x11-extension-implementation.h
index 2a70eafd93..a443b7ec1a 100644
--- a/epan/dissectors/x11-extension-implementation.h
+++ b/epan/dissectors/x11-extension-implementation.h
@@ -25,7 +25,9 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#if defined(__GNUC__)
 #pragma GCC diagnostic ignored "-Wunused-but-set-variable"
+#endif
 
 #include "x11-glx-render-enum.h"
 
diff --git a/tools/process-x11-xcb.pl b/tools/process-x11-xcb.pl
index 6a648fc8cf..38ac60a8d1 100755
--- a/tools/process-x11-xcb.pl
+++ b/tools/process-x11-xcb.pl
@@ -1383,7 +1383,9 @@ if (-e "$mesadir/gl_API.xml") {
 	    or die ("Cannot open x11-glx-render-enum.h for writing\n");
     add_generated_header($enum, 'mesa');
     print $enum "static const value_string mesa_enum[] = {\n";
-    print $impl '#pragma GCC diagnostic ignored "-Wunused-but-set-variable"'."\n\n";
+    print $impl "#if defined(__GNUC__)\n";
+    print $impl '#pragma GCC diagnostic ignored "-Wunused-but-set-variable"'."\n";
+    print $impl "#endif\n\n";
     print $impl '#include "x11-glx-render-enum.h"'."\n\n";
 
     print("Mesa glRender:\n");