diff --git a/src/backend/replication/syncrep.c b/src/backend/replication/syncrep.c
index d5868d66b7d5c311a1298f56b561ed7a3f5b87c7..0033b5559f382a33b58f5489c1f56214a7466ea3 100644
--- a/src/backend/replication/syncrep.c
+++ b/src/backend/replication/syncrep.c
@@ -447,9 +447,9 @@ SyncRepGetStandbyPriority(void)
 }
 
 /*
- * Walk queue from head setting setting the state of any backends that
- * need to be woken, remove them from the queue and then wake them.
- * Set all = true to wake whole queue, or just up to LSN.
+ * Walk queue from head.  Set the state of any backends that need to be woken,
+ * remove them from the queue, and then wake them.  Pass all = true to wake
+ * whole queue; otherwise, just wake up to the walsender's LSN.
  *
  * Must hold SyncRepLock.
  */
diff --git a/src/backend/storage/ipc/shmqueue.c b/src/backend/storage/ipc/shmqueue.c
index 5d684b2b85fdc8d3a9f8299dacc611657dbd8ecf..d7ec3013a6e148190626209cb135a46697dda817 100644
--- a/src/backend/storage/ipc/shmqueue.c
+++ b/src/backend/storage/ipc/shmqueue.c
@@ -157,7 +157,7 @@ SHMQueueNext(const SHM_QUEUE *queue, const SHM_QUEUE *curElem, Size linkOffset)
 /*--------------------
  * SHMQueuePrev -- Get the previous element from a queue
  *
- * Same as SHMQueueNext, just starting at tail and moving towards head
+ * Same as SHMQueueNext, just starting at tail and moving towards head.
  * All other comments and usage applies.
  */
 Pointer
diff --git a/src/include/replication/syncrep.h b/src/include/replication/syncrep.h
index fb86e9e8d65d0a2e480296a27aee7711d40968b2..1c6d39238c4a63d5ef6c5bbffc790136e76cb361 100644
--- a/src/include/replication/syncrep.h
+++ b/src/include/replication/syncrep.h
@@ -29,7 +29,6 @@
 
 /* user-settable parameters for synchronous replication */
 extern bool sync_rep_mode;
-extern int 	sync_rep_timeout;
 extern char *SyncRepStandbyNames;
 
 /* called by user backend */
@@ -44,6 +43,6 @@ extern void SyncRepReleaseWaiters(void);
 
 /* called by various procs */
 extern int SyncRepWakeQueue(bool all);
-const char *assign_synchronous_standby_names(const char *newval, bool doit, GucSource source);
+extern const char *assign_synchronous_standby_names(const char *newval, bool doit, GucSource source);
 
 #endif   /* _SYNCREP_H */