diff --git a/api/routes_app_installations.go b/api/routes_app_installations.go
index 30c037c..f76d7c2 100644
--- a/api/routes_app_installations.go
+++ b/api/routes_app_installations.go
@@ -30,7 +30,7 @@ func (a *appInstallApi) handlerAppGetAccessToken(w http.ResponseWriter, r *http.
 	now := time.Now().Add(-30 * time.Second)
 	expirationTime := now.Add(10 * time.Minute)
 
-	appId := mux.Vars(r)["app_id"]
+	appId := mux.Vars(r)["installation_id"]
 	appIdInt, err := strconv.ParseInt(appId, 10, 64)
 
 	if err != nil {