diff --git a/src/regex.c b/src/regex.c
index 940c95f448a..f8e2dcb27f5 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -68,6 +68,7 @@
 #include "category.h"
 
 #define malloc xmalloc
+#define realloc xrealloc
 #define free xfree
 
 #else  /* not emacs */