diff --git a/char32.c b/char32.c
index 69ccc232..6bd90e36 100644
--- a/char32.c
+++ b/char32.c
@@ -6,6 +6,7 @@
 
 #include <wctype.h>
 #include <wchar.h>
+#include <stdc-predef.h>
 
 
 #define LOG_MODULE "char32"