diff --git a/indra/newview/llvovolume.h b/indra/newview/llvovolume.h
index 8b7dc172e..71e4f0323 100644
--- a/indra/newview/llvovolume.h
+++ b/indra/newview/llvovolume.h
@@ -37,6 +37,8 @@
 #include "llviewertexture.h"
 #include "llframetimer.h"
 #include "llapr.h"
+#include "m3math.h"		// LLMatrix3
+#include "m4math.h"		// LLMatrix4
 #include <map>
 
 class LLViewerTextureAnim;