diff --git a/test/webfuse/mocks/mock_invokation_handler.hpp b/test/webfuse/mocks/mock_invokation_handler.hpp
index ba63130..9a70482 100644
--- a/test/webfuse/mocks/mock_invokation_handler.hpp
+++ b/test/webfuse/mocks/mock_invokation_handler.hpp
@@ -1,13 +1,13 @@
 #ifndef WF_MOCK_INVOKATION_HANDLER_HPP
 #define WF_MOCK_INVOKATION_HANDLER_HPP
 
-#include "webfuse/test_util/ws_server.hpp"
+#include "webfuse/test_util/invokation_handler.hpp"
 #include <gtest/gtest.h>
 
 namespace webfuse_test
 {
 
-class MockInvokationHander: public IIvokationHandler
+class MockInvokationHander: public InvokationHandler
 {
 public:
     MOCK_METHOD2(Invoke, std::string(char const * method, json_t * params));
diff --git a/test/webfuse/test_util/invokation_handler.hpp b/test/webfuse/test_util/invokation_handler.hpp
new file mode 100644
index 0000000..ac8b7fe
--- /dev/null
+++ b/test/webfuse/test_util/invokation_handler.hpp
@@ -0,0 +1,19 @@
+#ifndef WF_TEST_UTIL_INVOKATION_HANDLER_HPP
+#define WF_TEST_UTIL_INVOKATION_HANDLER_HPP
+
+#include <jansson.h>
+#include <string>
+
+namespace webfuse_test
+{
+
+class InvokationHandler
+{
+public:
+    virtual ~InvokationHandler() = default;
+    virtual std::string Invoke(char const * method, json_t * params) = 0;
+};
+
+}
+
+#endif
diff --git a/test/webfuse/test_util/ws_server.cc b/test/webfuse/test_util/ws_server.cc
index e76264d..e2161d5 100644
--- a/test/webfuse/test_util/ws_server.cc
+++ b/test/webfuse/test_util/ws_server.cc
@@ -1,4 +1,5 @@
 #include "webfuse/test_util/ws_server.hpp"
+#include "webfuse/test_util/invokation_handler.hpp"
 #include "webfuse/impl/util/lws_log.h"
 
 #include <libwebsockets.h>
@@ -75,7 +76,7 @@ class WsServer::Private : public IServer
     Private(Private const &) = delete;
     Private & operator=(Private const &) = delete;
 public:
-    Private(IIvokationHandler & handler, std::string const & protocol, int port, bool enable_tls);
+    Private(InvokationHandler & handler, std::string const & protocol, int port, bool enable_tls);
     ~Private();
     std::string const & GetUrl() const;
     void OnConnected(lws * wsi) override;
@@ -88,7 +89,7 @@ public:
 private:
     static void Run(Private * self);
 
-    IIvokationHandler & handler_;
+    InvokationHandler & handler_;
     std::string protocol_;
     bool is_shutdown_requested;
     lws * wsi_;
@@ -102,7 +103,7 @@ private:
 };
 
 WsServer::WsServer(
-    IIvokationHandler& handler,
+    InvokationHandler& handler,
     std::string const & protocol,
     int port,
     bool enable_tls)
@@ -133,7 +134,7 @@ void WsServer::SendMessage(json_t * message)
 
 
 WsServer::Private::Private(
-    IIvokationHandler & handler,
+    InvokationHandler & handler,
     std::string const & protocol,
     int port,
     bool enable_tls)
diff --git a/test/webfuse/test_util/ws_server.hpp b/test/webfuse/test_util/ws_server.hpp
index cced6ef..e8b0dfe 100644
--- a/test/webfuse/test_util/ws_server.hpp
+++ b/test/webfuse/test_util/ws_server.hpp
@@ -7,12 +7,7 @@
 namespace webfuse_test
 {
 
-class IIvokationHandler
-{
-public:
-    virtual ~IIvokationHandler() = default;
-    virtual std::string Invoke(char const * method, json_t * params) = 0;
-};
+class InvokationHandler;
 
 class WsServer
 {
@@ -20,7 +15,7 @@ class WsServer
     WsServer & operator=(WsServer const & ) = delete;
 public:
     WsServer(
-        IIvokationHandler& handler,
+        InvokationHandler& handler,
         std::string const & protocol,
         int port = 0,
         bool enable_tls = false);