diff --git a/platform-independent/c/core/src/mpw-types.h b/platform-independent/c/core/src/mpw-types.h
index b342b58c..24a1dab5 100644
--- a/platform-independent/c/core/src/mpw-types.h
+++ b/platform-independent/c/core/src/mpw-types.h
@@ -25,6 +25,7 @@
 #endif
 
 MP_LIBS_BEGIN
+#define __STDC_WANT_LIB_EXT1__ 1
 #include <stdlib.h>
 #include <stdint.h>
 #include <stdbool.h>