diff --git a/src/md5.h b/src/md5.h
index 2da4a78f..6d243307 100644
--- a/src/md5.h
+++ b/src/md5.h
@@ -16,6 +16,10 @@
 #include "config.h"
 #include "compat.h"
 
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
 #define HASH_LEN     16
 
 struct MD5Context