--- a/js/src/frontend/BinSource.cpp
+++ b/js/src/frontend/BinSource.cpp
@@ -83,16 +83,24 @@ public:
     ASTReader(JSContext* cx_, LifoAlloc& alloc_)
         : AutoGCRooter(cx_, BINPARSER)
         , traceListHead(nullptr)
         , allocator(cx_, alloc_)
         , cx(cx_)
         , alloc(alloc_)
     { }
 
+    static bool test() {
+        // FIXME: Just a small hack to force the build system to
+        // display undefined symbols.
+        ASTReader foo(nullptr, *static_cast<LifoAlloc*>(nullptr));
+        UniquePtr<ParseNode> out;
+        return foo.parse(nullptr, nullptr, nullptr, out);
+    }
+
     bool parse(char* start, char* stop, GlobalSharedContext* sc, UniquePtr<ParseNode>& out);
 private:
     bool raiseError();
 
     // --- Parse full nodes.
 
     bool parseBool(SimpleTokenReader*, Maybe<bool>*);
     bool parseProgram(SimpleTokenReader* reader, UniquePtr<ParseNode>& out);
@@ -1980,12 +1988,12 @@ ASTReader::raiseError() {
 }
 
 void
 TraceBinParser(JSTracer* trc, AutoGCRooter* parser)
 {
     static_cast<ASTReader*>(parser)->trace(trc);
 }
 
-static ASTReader foo(nullptr, *static_cast<LifoAlloc*>(nullptr));
+static bool NOTHING = ASTReader::test();
 
 } // namespace frontend
 } // namespace js