diff --git a/apps/emqx_prometheus/test/emqx_prometheus_SUITE.erl b/apps/emqx_prometheus/test/emqx_prometheus_SUITE.erl
index 03e8d6d78..16590b114 100644
--- a/apps/emqx_prometheus/test/emqx_prometheus_SUITE.erl
+++ b/apps/emqx_prometheus/test/emqx_prometheus_SUITE.erl
@@ -22,14 +22,14 @@
 -compile(export_all).
 
 -define(CLUSTER_RPC_SHARD, emqx_cluster_rpc_shard).
--define(CONF_DEFAULT,
-    <<"\n"
+-define(CONF_DEFAULT, <<
+    "\n"
     "prometheus {\n"
     "  push_gateway_server = \"http://127.0.0.1:9091\"\n"
     "  interval = \"1s\"\n"
     "  enable = true\n"
-    "}\n">>
-).
+    "}\n"
+>>).
 
 %%--------------------------------------------------------------------
 %% Setups