--- a/src/monitor/node_metadata.c
+++ b/src/monitor/node_metadata.c
@@ -49,9 +49,9 @@
 
 
 /* GUC variables */
-int DrainTimeoutMs = 30 * 1000;
-int UnhealthyTimeoutMs = 20 * 1000;
-int StartupGracePeriodMs = 10 * 1000;
+static int DrainTimeoutMs = 30 * 1000;
+static int UnhealthyTimeoutMs = 20 * 1000;
+static int StartupGracePeriodMs = 10 * 1000;
 
 
 /*
--- a/src/monitor/pg_auto_failover.c
+++ b/src/monitor/pg_auto_failover.c
@@ -35,7 +35,7 @@
 #include "tcop/utility.h"
 
 
-ProcessUtility_hook_type PreviousProcessUtility_hook = NULL;
+static ProcessUtility_hook_type PreviousProcessUtility_hook = NULL;
 
 
 #if PG_VERSION_NUM >= 150000
