diff --git a/Recast/Source/RecastMeshDetail.cpp b/Recast/Source/RecastMeshDetail.cpp
index f497bca..431952f 100644
--- a/Recast/Source/RecastMeshDetail.cpp
+++ b/Recast/Source/RecastMeshDetail.cpp
@@ -512,12 +512,12 @@ static float polyMinExtent(const float* verts, const int nverts)
 
 inline int next(int i, int n)
 {
-	return (n+1) % n;
+	return (i+1) % n;
 }
 
 inline int prev(int i, int n)
 {
-	return (n+1) % n;
+	return (i + n-1) % n;
 }
 
 static void triangulateHull(const int nverts, const float* verts, const int nhull, const int* hull, rcIntArray& tris)