diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 6f9aaa52fa..6ad504453b 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -267,6 +267,13 @@ InitProcGlobal(void)
 
 		/* Initialize lockGroupMembers list. */
 		dlist_init(&procs[i].lockGroupMembers);
+
+		/*
+		 * Initialize the atomic variables, otherwise, it won't be safe to
+		 * access them for backends that aren't currently in use.
+		 */
+		pg_atomic_init_u32(&(procs[i].procArrayGroupNext), INVALID_PGPROCNO);
+		pg_atomic_init_u32(&(procs[i].clogGroupNext), INVALID_PGPROCNO);
 	}
 
 	/*
@@ -401,7 +408,7 @@ InitProcess(void)
 	/* Initialize fields for group XID clearing. */
 	MyProc->procArrayGroupMember = false;
 	MyProc->procArrayGroupMemberXid = InvalidTransactionId;
-	pg_atomic_init_u32(&MyProc->procArrayGroupNext, INVALID_PGPROCNO);
+	Assert(pg_atomic_read_u32(&MyProc->procArrayGroupNext) == INVALID_PGPROCNO);
 
 	/* Check that group locking fields are in a proper initial state. */
 	Assert(MyProc->lockGroupLeader == NULL);
@@ -416,7 +423,7 @@ InitProcess(void)
 	MyProc->clogGroupMemberXidStatus = TRANSACTION_STATUS_IN_PROGRESS;
 	MyProc->clogGroupMemberPage = -1;
 	MyProc->clogGroupMemberLsn = InvalidXLogRecPtr;
-	pg_atomic_init_u32(&MyProc->clogGroupNext, INVALID_PGPROCNO);
+	Assert(pg_atomic_read_u32(&MyProc->clogGroupNext) == INVALID_PGPROCNO);
 
 	/*
 	 * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch