diff --git a/third_party/libtess2/src/Source/sweep.c b/third_party/libtess2/src/Source/sweep.c
index 31e050efc85a8..d18ad92de91ad 100644
--- a/third_party/libtess2/src/Source/sweep.c
+++ b/third_party/libtess2/src/Source/sweep.c
@@ -1159,7 +1159,9 @@ static void DoneEdgeDict( TESStesselator *tess )
 		*/
 		if( ! reg->sentinel ) {
 			tess_assert( reg->fixUpperEdge );
+#ifndef NDEBUG
 			tess_assert( ++fixedEdges == 1 );
+#endif
 		}
 		tess_assert( reg->windingNumber == 0 );
 		DeleteRegion( tess, reg );