diff --git a/indra/llrender/llrender.cpp b/indra/llrender/llrender.cpp
index 69420dd0bb338b07539a62847916ddfdc443743b..0e242a20f697c3d23d590eab9086939ae7a55ab0 100644
--- a/indra/llrender/llrender.cpp
+++ b/indra/llrender/llrender.cpp
@@ -2039,7 +2039,8 @@ void LLRender::vertexBatchPreTransformed(LLVector3* verts, S32 vert_count)
 		}
 	}
 
-	mVerticesp[mCount] = mVerticesp[mCount-1];
+	if( mCount > 0 ) // ND: Guard against crashes if mCount is zero, yes it can happen
+		mVerticesp[mCount] = mVerticesp[mCount-1];
 }
 
 void LLRender::vertexBatchPreTransformed(LLVector3* verts, LLVector2* uvs, S32 vert_count)