diff --git a/docker/backend/mempool-config.json b/docker/backend/mempool-config.json
index 457eccd4a..712b95b3e 100644
--- a/docker/backend/mempool-config.json
+++ b/docker/backend/mempool-config.json
@@ -70,7 +70,7 @@
     "USERNAME": "__DATABASE_USERNAME__",
     "PASSWORD": "__DATABASE_PASSWORD__",
     "TIMEOUT": __DATABASE_TIMEOUT__,
-    "PID_DIR": "__DATABASE_PID_DIR__",
+    "PID_DIR": "__DATABASE_PID_DIR__"
   },
   "SYSLOG": {
     "ENABLED": __SYSLOG_ENABLED__,