diff --git a/public/amtl/am-hashtable.h b/public/amtl/am-hashtable.h
index de0a7259..7e04a0b6 100644
--- a/public/amtl/am-hashtable.h
+++ b/public/amtl/am-hashtable.h
@@ -353,7 +353,7 @@ class HashTable : public AllocPolicy
   }
 
  public:
-  HashTable(AllocPolicy ap)
+  HashTable(AllocPolicy ap = AllocPolicy())
   : AllocPolicy(ap),
     capacity_(0),
     nelements_(0),
@@ -420,6 +420,9 @@ class HashTable : public AllocPolicy
   bool add(Insert &i, const Payload &payload) {
     return internalAdd(i, payload);
   }
+  bool add(Insert &i) {
+    return internalAdd(i, Payload());
+  }
 
   bool checkDensity() {
     if (underloaded())