diff --git a/3rdparty/forsyth-too/forsythtriangleorderoptimizer.cpp b/3rdparty/forsyth-too/forsythtriangleorderoptimizer.cpp
index 0dd59c63..aa1f7935 100644
--- a/3rdparty/forsyth-too/forsythtriangleorderoptimizer.cpp
+++ b/3rdparty/forsyth-too/forsythtriangleorderoptimizer.cpp
@@ -293,7 +293,7 @@ namespace Forsyth
 
                 assert(vertexData.activeFaceListSize > 0);
                 uint* begin = &activeFaceList[vertexData.activeFaceListStart];
-                uint* end = &activeFaceList[vertexData.activeFaceListStart + vertexData.activeFaceListSize];
+				uint* end = &(activeFaceList[vertexData.activeFaceListStart + vertexData.activeFaceListSize - 1]) + 1;
                 uint* it = std::find(begin, end, bestFace);
                 assert(it != end);
                 std::swap(*it, *(end-1));