diff --git a/test/cpp/src/TestServer.cpp b/test/cpp/src/TestServer.cpp
index 6d2a260..2705064 100644
--- a/test/cpp/src/TestServer.cpp
+++ b/test/cpp/src/TestServer.cpp
@@ -98,6 +98,13 @@
     return thing;
   }
 
+  void testBinary(std::string& _return, const std::string& thing) {
+    std::ostringstream hexstr;
+    hexstr << std::hex << thing;
+    printf("testBinary(%s)\n", hexstr.str().c_str());
+    _return = thing;
+  }
+
   void testStruct(Xtruct& out, const Xtruct& thing) {
     printf("testStruct({\"%s\", %d, %d, %" PRId64 "})\n",
            thing.string_thing.c_str(),
@@ -411,6 +418,12 @@
     cob(res);
   }
 
+  virtual void testBinary(tcxx::function<void(std::string const& _return)> cob, const std::string& thing) {
+    std::string res;
+    _delegate->testBinary(res, thing);
+    cob(res);
+  }
+
   virtual void testStruct(tcxx::function<void(Xtruct const& _return)> cob, const Xtruct& thing) {
     Xtruct res;
     _delegate->testStruct(res, thing);