diff --git a/plugin.sh b/plugin.sh
index 7d033e7..672f305 100755
--- a/plugin.sh
+++ b/plugin.sh
@@ -52,7 +52,7 @@ run_docker_cp() {
   
   echo "--- start exec ---"
   if [ -n "$PLUGIN_EXEC" ]; then
-	docker -H "$REMOTE_DOCKER_HOST" exec "$CONTAINER" sh -c "eval `ssh-agent` && echo \"$PLUGIN_DEPLOY_KEY\" | ssh-add - && $PLUGIN_EXEC"
+	docker -H "$REMOTE_DOCKER_HOST" exec "$CONTAINER" sh -c "eval $(ssh-agent) && echo \"$PLUGIN_DEPLOY_KEY\" | ssh-add - && $PLUGIN_EXEC"
   fi
   echo "--- end exec ---"