diff --git a/include/qbsp/warnerr.hh b/include/qbsp/warnerr.hh
index dcb8b4e8..853e3437 100644
--- a/include/qbsp/warnerr.hh
+++ b/include/qbsp/warnerr.hh
@@ -20,6 +20,8 @@
 */
 // warnerr.h
 
+#pragma once
+
 enum
 {
     warnNoWadKey, // 0