--- a/js/public/GCHashTable.h
+++ b/js/public/GCHashTable.h
@@ -551,21 +551,16 @@ class WeakCache<GCHashMap<Key, Value, Ha
     }
 
     void remove(const Lookup& l) {
         Ptr p = lookup(l);
         if (p)
             remove(p);
     }
 
-    template<typename KeyInput>
-    bool add(AddPtr& p, KeyInput&& k) {
-        return map.add(p, std::forward<KeyInput>(k));
-    }
-
     template<typename KeyInput, typename ValueInput>
     bool add(AddPtr& p, KeyInput&& k, ValueInput&& v) {
         return map.add(p, std::forward<KeyInput>(k), std::forward<ValueInput>(v));
     }
 
     template<typename KeyInput, typename ValueInput>
     bool relookupOrAdd(AddPtr& p, KeyInput&& k, ValueInput&& v) {
         return map.relookupOrAdd(p, std::forward<KeyInput>(k), std::forward<ValueInput>(v));

--- a/js/src/jsapi-tests/testGCWeakCache.cpp
+++ b/js/src/jsapi-tests/testGCWeakCache.cpp
@@ -644,17 +644,17 @@ TestReplaceDyingInMap()
     CHECK(!cache.has(6));
 
     auto ptr = cache.lookupForAdd(2);
     CHECK(!ptr);
     CHECK(cache.add(ptr, 2, value1));
 
     auto ptr2 = cache.lookupForAdd(3);
     CHECK(!ptr2);
-    CHECK(cache.add(ptr2, 3));
+    CHECK(cache.add(ptr2, 3, JS::Heap<JSObject*>()));
 
     auto ptr3 = cache.lookupForAdd(4);
     CHECK(!ptr3);
     CHECK(cache.relookupOrAdd(ptr3, 4, value1));
 
     CHECK(cache.put(5, value1));
     CHECK(cache.putNew(6, value1));
 

--- a/mfbt/HashTable.h
+++ b/mfbt/HashTable.h
@@ -344,23 +344,16 @@ public:
   // Add a key/value. Returns false on OOM.
   template<typename KeyInput, typename ValueInput>
   MOZ_MUST_USE bool add(AddPtr& aPtr, KeyInput&& aKey, ValueInput&& aValue)
   {
     return mImpl.add(
       aPtr, std::forward<KeyInput>(aKey), std::forward<ValueInput>(aValue));
   }
 
-  // Add a given key and a default value. Returns false on OOM.
-  template<typename KeyInput>
-  MOZ_MUST_USE bool add(AddPtr& aPtr, KeyInput&& aKey)
-  {
-    return mImpl.add(aPtr, std::forward<KeyInput>(aKey), Value());
-  }
-
   // See the comment above lookupForAdd() for details.
   template<typename KeyInput, typename ValueInput>
   MOZ_MUST_USE bool relookupOrAdd(AddPtr& aPtr,
                                   KeyInput&& aKey,
                                   ValueInput&& aValue)
   {
     return mImpl.relookupOrAdd(aPtr,
                                aKey,