diff --git a/UnitySDK/Assets/TiltBrush/Scripts/Editor/ParticleMesh.cs b/UnitySDK/Assets/TiltBrush/Scripts/Editor/ParticleMesh.cs
index 10f02b1..8e29b39 100644
--- a/UnitySDK/Assets/TiltBrush/Scripts/Editor/ParticleMesh.cs
+++ b/UnitySDK/Assets/TiltBrush/Scripts/Editor/ParticleMesh.cs
@@ -58,8 +58,8 @@ internal static void FilterMesh(Mesh mesh, WarningCallback callback) {
     ParticleMesh src = ParticleMesh.FromMesh(mesh);
     ParticleMesh dst = new ParticleMesh();
 
-    // ClassifyQuad wants at least 6 verts to examine
-    int limit = src.VertexCount - 5;
+    // ClassifyQuad wants at least 6 indices (2 triangles) to examine
+    int limit = src.TriangleCount - 6;
     int iiVert = 0;
     while (iiVert < limit) {
       switch (src.ClassifyQuad(iiVert, callback)) {
@@ -109,7 +109,7 @@ private static ParticleMesh FromMesh(Mesh mesh) {
   bool m_bNoisy = true;
   int? m_lastMod;
 
-  internal int VertexCount { get { return m_vertices.Count; } }
+  internal int TriangleCount { get { return m_triangles.Count; } }
 
   // iiVert is an index to an index to a vert (an index into m_triangles)
   // iiVert must be at least 6 verts from the end of the mesh.