diff --git a/src/openssl-engine.hxx b/src/openssl-engine.hxx
index 5b40e0c..5dc4e83 100644
--- a/src/openssl-engine.hxx
+++ b/src/openssl-engine.hxx
@@ -79,9 +79,11 @@ namespace openssl {
       }
       virtual ~Engine() {
         OPENSSL_LOG("log");
-        // removed EngineMapper::destroy because of crash:
-        // https://dev.marc.waeckerlin.org/projects/libpcscxx/ticket/25
-        //OPENSSL_CHECK(ENGINE_free(_e));
+        if (_e) {
+          OPENSSL_LOG("free the engine");
+          OPENSSL_CHECK(ENGINE_free(_e));
+          _e = 0;
+        }
       }
       virtual const char* id() = 0;
       virtual const char* name() = 0;
@@ -147,10 +149,8 @@ namespace openssl {
         _map[e->_e] = e;
         OPENSSL_CHECK(ENGINE_set_id(e->_e, e->id()));
         OPENSSL_CHECK(ENGINE_set_name(e->_e, e->name()));
-        // removed EngineMapper::destroy because of crash:
-        // https://dev.marc.waeckerlin.org/projects/libpcscxx/ticket/25
-        //OPENSSL_CHECK(ENGINE_set_destroy_function
-        //              (e->_e, EngineMapper::destroy));
+        OPENSSL_CHECK(ENGINE_set_destroy_function
+                      (e->_e, EngineMapper::destroy));
         OPENSSL_CHECK(ENGINE_set_init_function(e->_e, EngineMapper::init));
         OPENSSL_CHECK(ENGINE_set_finish_function(e->_e, EngineMapper::finish));
         OPENSSL_CHECK(ENGINE_set_ctrl_function(e->_e, EngineMapper::ctrl));
@@ -173,10 +173,15 @@ namespace openssl {
 
       static void remove(Engine *e) {
         OPENSSL_LOG("log");
-        OPENSSL_CHECK(ENGINE_remove(e->_e));
-        OPENSSL_CHECK(ENGINE_finish(e->_e));
-        _map.erase(e->_e);
-        delete e;
+        if (e) {
+          OPENSSL_LOG("call remove: e->_e = "<<((void*)e->_e));
+          OPENSSL_CHECK(ENGINE_remove(e->_e));
+          OPENSSL_LOG("call finish");
+          OPENSSL_CHECK(ENGINE_finish(e->_e));
+          OPENSSL_LOG("erase from map");
+          _map.erase(e->_e);
+          delete e; e=0;
+        }
       }
       
     private:
@@ -193,6 +198,7 @@ namespace openssl {
       static int finish(ENGINE* e) {
         OPENSSL_LOG("log");
         Map::iterator it(_map.find(e));
+        OPENSSL_LOG("finish: "<<(it!=_map.end()?"true":"false"));
         return it!=_map.end()?it->second->finish():0;
       }
       static int ctrl(ENGINE* e, int cmd, long i, void* p, void(*f)()) {