diff --git a/js/src/jstracer.cpp b/js/src/jstracer.cpp
index 52ef0c61eab..bd2f90353ad 100644
--- a/js/src/jstracer.cpp
+++ b/js/src/jstracer.cpp
@@ -7162,6 +7162,8 @@ TraceRecorder::record_JSOP_GETELEM()
 
     /* Property access using a string name or something we have to stringify. */
     if (!JSVAL_IS_INT(idx)) {
+        if (!JSVAL_IS_PRIMITIVE(idx))
+            ABORT_TRACE("non-primitive index");
         // If index is not a string, turn it into a string.
         if (!js_InternNonIntElementId(cx, obj, idx, &id))
             ABORT_TRACE("failed to intern non-int element id");