diff --git a/sys/sys/lockmgr.h b/sys/sys/lockmgr.h
index bef9f039b8c..c04390f07a3 100644
--- a/sys/sys/lockmgr.h
+++ b/sys/sys/lockmgr.h
@@ -58,7 +58,7 @@
 #ifdef _KERNEL
 
 #if !defined(LOCK_FILE) || !defined(LOCK_LINE)
-#error	"LOCK_FILE and LOCK_LINE not defined, include <sys/lock.h> before"
+#error	"LOCK_FILE and LOCK_LINE not defined, include <sys/_lock.h> before"
 #endif
 
 struct thread;