--- a/js/src/asmjs/WasmBinaryIterator.h
+++ b/js/src/asmjs/WasmBinaryIterator.h
@@ -167,22 +167,22 @@ class TypeAndValue
     }
     void setValue(Value value) {
         value_ = value;
     }
 };
 
 // Specialization for when there is no additional data needed.
 template <>
-struct TypeAndValue<Nothing>
+class TypeAndValue<Nothing>
 {
     ExprType type_;
 
   public:
-    TypeAndValue() {}
+    TypeAndValue() = default;
     explicit TypeAndValue(ExprType type) : type_(type) {}
 
     TypeAndValue(ExprType type, Nothing value)
       : type_(type)
     {}
 
     ExprType type() const { return type_; }
     Nothing value() const { return Nothing(); }