diff --git a/js/src/jsinfer.cpp b/js/src/jsinfer.cpp
index bae334abc56..508eb23b141 100644
--- a/js/src/jsinfer.cpp
+++ b/js/src/jsinfer.cpp
@@ -378,7 +378,7 @@ TypeSet::intersectionEmpty(TypeSet *other)
     if (unknown() || other->unknown())
         return false;
 
-    if (unknownObject() && unknownObject())
+    if (unknownObject() && other->unknownObject())
         return false;
 
     if (unknownObject() && other->getObjectCount() > 0)
@@ -392,12 +392,14 @@ TypeSet::intersectionEmpty(TypeSet *other)
         return false;
 
     // Test if there are object that are in both TypeSets
-    for (unsigned i = 0; i < getObjectCount(); i++) {
-        TypeObjectKey *obj = getObject(i);
-        if (!obj)
-            continue;
-        if (other->hasType(Type::ObjectType(obj)))
-            return false;
+    if (!unknownObject()) {
+        for (unsigned i = 0; i < getObjectCount(); i++) {
+            TypeObjectKey *obj = getObject(i);
+            if (!obj)
+                continue;
+            if (other->hasType(Type::ObjectType(obj)))
+                return false;
+        }
     }
 
     return true;