diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 23fce948967..8dbfaffaa9a 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -327,6 +327,7 @@ WalReceiverMain(const void *startup_data, size_t startup_data_len)
 					 errdetail("The primary's identifier is %s, the standby's identifier is %s.",
 							   primary_sysid, standby_sysid)));
 		}
+		pfree(primary_sysid);
 
 		/*
 		 * Confirm that the current timeline of the primary is the same or