diff --git a/include/wx/hashmap.h b/include/wx/hashmap.h
index 4d046de57f..1cff98219b 100644
--- a/include/wx/hashmap.h
+++ b/include/wx/hashmap.h
@@ -13,6 +13,7 @@
 #define _WX_HASHMAP_H_
 
 #include "wx/string.h"
+#include "wx/wxcrt.h"
 
 #if (defined(HAVE_EXT_HASH_MAP) || defined(HAVE_HASH_MAP)) \
     && (defined(HAVE_GNU_CXX_HASH_MAP) || defined(HAVE_STD_HASH_MAP))