diff --git a/include/dm/util.h b/include/dm/util.h
index 8be64a921d..6ac3a38ef0 100644
--- a/include/dm/util.h
+++ b/include/dm/util.h
@@ -5,6 +5,7 @@
  */
 
 #ifndef __DM_UTIL_H
+#define __DM_UTIL_H
 
 void dm_warn(const char *fmt, ...);