diff --git a/indra/llxml/llcontrol.h b/indra/llxml/llcontrol.h
index 4bc76802f83846a2310b313a4be0efbeb7fec2be..54f90b6a741ee11feca3b7f676152a004107bcd5 100644
--- a/indra/llxml/llcontrol.h
+++ b/indra/llxml/llcontrol.h
@@ -67,6 +67,7 @@ class LLVector3;
 class LLVector3d;
 class LLQuaternion;
 class LLColor4;
+class LLColor4U;
 class LLColor3;
 
 // if this is changed, also modify mTypeString in llcontrol.h