diff --git a/public/tier1/utlcommon.h b/public/tier1/utlcommon.h
index 9a4e1341..977c42d9 100644
--- a/public/tier1/utlcommon.h
+++ b/public/tier1/utlcommon.h
@@ -10,6 +10,8 @@
 #define UTLCOMMON_H
 #pragma once
 
+#include "utlstring.h"
+
 //-----------------------------------------------------------------------------
 // Henry Goffin (henryg) was here. Questions? Bugs? Go slap him around a bit.
 //-----------------------------------------------------------------------------