diff --git a/Source/o_vscanf.c b/Source/o_vscanf.c
index 6a363791a..d54151154 100644
--- a/Source/o_vscanf.c
+++ b/Source/o_vscanf.c
@@ -59,6 +59,7 @@ Cambridge, MA 02139, USA.  */
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <objc/objc-api.h>
 
 extern double strtod(const char *str, char **ptr);
 extern long strtol(const char *str, char** ptr, int base);