2 files changed, 10 insertions, 1 deletions
diff --git a/src/support/utilities.h b/src/support/utilities.h
index 57d170269..a8acfeed7 100644
--- a/src/support/utilities.h
+++ b/src/support/utilities.h
@@ -64,7 +64,7 @@ std::unique_ptr<T> make_unique(Args&&... args) {
 class Fatal {
 public:
   Fatal() { std::cerr << "Fatal: "; }
-  template<typename T> Fatal& operator<<(T arg) {
+  template<typename T> Fatal& operator<<(T&& arg) {
     std::cerr << arg;
     return *this;
   }
diff --git a/src/wasm.h b/src/wasm.h
index eb5c15514..65f70cef9 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -746,6 +746,15 @@ public:
 
   Expression(Id id) : _id(id) {}
 
+protected:
+  // An expression cannot be constructed without knowing what kind of expression
+  // it should be.
+  Expression(const Expression& other) = default;
+  Expression(Expression&& other) = default;
+  Expression& operator=(Expression& other) = default;
+  Expression& operator=(Expression&& other) = default;
+
+public:
   void finalize() {}
 
   template<class T> bool is() const {