diff --git a/libraries/fbx/src/FBXReader.cpp b/libraries/fbx/src/FBXReader.cpp
index 223a633365..cf11706ede 100644
--- a/libraries/fbx/src/FBXReader.cpp
+++ b/libraries/fbx/src/FBXReader.cpp
@@ -76,7 +76,9 @@ bool FBXGeometry::convexHullContains(const glm::vec3& point) const {
 
     auto checkEachPrimitive = [=](FBXMesh& mesh, QVector<int> indices, int primitiveSize) -> bool {
         // Check whether the point is "behind" all the primitives.
-        for (int j = 0; j < indices.size() - 2; j += primitiveSize) {
+        for (int j = 0;
+             j < indices.size() - 2; // -2 in case the vertices aren't the right size -- we access j + 2 below
+             j += primitiveSize) {
             if (!isPointBehindTrianglesPlane(point,
                                              mesh.vertices[indices[j]],
                                              mesh.vertices[indices[j + 1]],