diff --git a/src/gui/GUI.cc b/src/gui/GUI.cc
index 5149807..9fbb2cb 100644
--- a/src/gui/GUI.cc
+++ b/src/gui/GUI.cc
@@ -49,7 +49,7 @@ namespace jes
         glClearColor (0.0, 0.0, 0.0, 0.0);
     }
 
-    void GUI::run()
+    int GUI::run()
     {
         glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
         SDL_GL_SwapWindow(m_window);
@@ -65,5 +65,7 @@ namespace jes
                     break;
             }
         }
+
+        return 0;
     }
 }
diff --git a/src/gui/GUI.h b/src/gui/GUI.h
index f7a3638..bab0e5b 100644
--- a/src/gui/GUI.h
+++ b/src/gui/GUI.h
@@ -10,7 +10,7 @@ namespace jes
     {
     public:
         GUI();
-        void run();
+        int run();
     protected:
         SDL_Window * m_window;
     };
diff --git a/src/gui/main.cc b/src/gui/main.cc
index f58d17a..5261424 100644
--- a/src/gui/main.cc
+++ b/src/gui/main.cc
@@ -6,5 +6,5 @@ using namespace std;
 int main(int argc, char *argv[])
 {
     jes::GUIRef gui = new jes::GUI();
-    gui->run();
+    return gui->run();
 }