diff --git a/src/regex/regc_locale.c b/src/regex/regc_locale.c
index 7428515054..15bcef32d1 100644
--- a/src/regex/regc_locale.c
+++ b/src/regex/regc_locale.c
@@ -16,7 +16,9 @@
  *  for wxWidgets are under the wxWidgets licence, see README for details.
  */
 
+#ifndef CONST
 #define CONST const
+#endif
 
 /* ASCII character-name table */