diff --git a/buildTree.js b/buildTree.js
index 86f631982..67a27d804 100644
--- a/buildTree.js
+++ b/buildTree.js
@@ -57,7 +57,8 @@ var groupTypes = {
             var atoms = prevAtom.value.value;
             prevAtom = atoms[atoms.length - 1];
         }
-        if (!prev || utils.contains(["bin", "open", "rel"], prevAtom.type)) {
+        if (!prev || utils.contains(["bin", "open", "rel", "op", "punct"],
+                prevAtom.type)) {
             group.type = "ord";
             className = "mord";
         }