diff --git a/doc/examples/openssl-engine-demo.cxx b/doc/examples/openssl-engine-demo.cxx
index 9b626ad..0cd52ec 100644
--- a/doc/examples/openssl-engine-demo.cxx
+++ b/doc/examples/openssl-engine-demo.cxx
@@ -25,7 +25,7 @@ class TestEngine: virtual public openssl::Engine {
 
 int main(int, char**) {
   {
-    openssl::RegisterEngine testEngine(new TestEngine);
+    openssl::RegisterEngine<> testEngine(new TestEngine);
     
     for (ENGINE* e(ENGINE_get_first()); e; e = ENGINE_get_next(e)) {
       std::cout<<"Found Engine: "<<ENGINE_get_id(e)<<std::endl;
diff --git a/src/openssl-engine.hxx b/src/openssl-engine.hxx
index 8c709ea..e7b8e9b 100644
--- a/src/openssl-engine.hxx
+++ b/src/openssl-engine.hxx
@@ -279,25 +279,31 @@ namespace openssl {
 
   //! Scoped Engine Registry
   /*! Engine will be deregistered and freed at destruction */
-  class RegisterEngine {
+  template <class ENGINE=Engine> class RegisterEngine {
     public:
-      RegisterEngine(Engine* e): _e(e) {
+      RegisterEngine(ENGINE* e = 0): _e(e) {
         if (_e) EngineMapper::add(_e);
       }
       ~RegisterEngine() {
         if (_e) EngineMapper::remove(_e);
       }
-      operator Engine*() {
+      RegisterEngine& operator=(ENGINE* e) {
+        if (_e) EngineMapper::remove(_e);
+        _e = e;
+        if (_e) EngineMapper::add(_e);
+        return *this;
+      }
+      operator ENGINE*() {
         return _e;
       }
-       Engine* operator->() {
+       ENGINE* operator->() {
         return _e;
       }
-       Engine& operator*() {
+       ENGINE& operator*() {
         return *_e;
       }
     private:
-      Engine* _e;
+      ENGINE* _e;
   };
 
   //@}