diff --git a/src/backend/replication/logical/origin.c b/src/backend/replication/logical/origin.c
index 1fc8f2dee9b..88fa35a9625 100644
--- a/src/backend/replication/logical/origin.c
+++ b/src/backend/replication/logical/origin.c
@@ -339,20 +339,26 @@ replorigin_drop(RepOriginId roident, bool nowait)
 
 	Assert(IsTransactionState());
 
+	/*
+	 * To interlock against concurrent drops, we hold ExclusiveLock on
+	 * pg_replication_origin throughout this funcion.
+	 */
 	rel = heap_open(ReplicationOriginRelationId, ExclusiveLock);
 
+	/*
+	 * First, clean up the slot state info, if there is any matching slot.
+	 */
 restart:
 	tuple = NULL;
-	/* cleanup the slot state info */
 	LWLockAcquire(ReplicationOriginLock, LW_EXCLUSIVE);
 
 	for (i = 0; i < max_replication_slots; i++)
 	{
 		ReplicationState *state = &replication_states[i];
 
-		/* found our slot */
 		if (state->roident == roident)
 		{
+			/* found our slot, is it busy? */
 			if (state->acquired_by != 0)
 			{
 				ConditionVariable *cv;
@@ -363,16 +369,23 @@ restart:
 							 errmsg("could not drop replication origin with OID %d, in use by PID %d",
 									state->roident,
 									state->acquired_by)));
+
+				/*
+				 * We must wait and then retry.  Since we don't know which CV
+				 * to wait on until here, we can't readily use
+				 * ConditionVariablePrepareToSleep (calling it here would be
+				 * wrong, since we could miss the signal if we did so); just
+				 * use ConditionVariableSleep directly.
+				 */
 				cv = &state->origin_cv;
 
 				LWLockRelease(ReplicationOriginLock);
-				ConditionVariablePrepareToSleep(cv);
+
 				ConditionVariableSleep(cv, WAIT_EVENT_REPLICATION_ORIGIN_DROP);
-				ConditionVariableCancelSleep();
 				goto restart;
 			}
 
-			/* first WAL log */
+			/* first make a WAL log entry */
 			{
 				xl_replorigin_drop xlrec;
 
@@ -382,7 +395,7 @@ restart:
 				XLogInsert(RM_REPLORIGIN_ID, XLOG_REPLORIGIN_DROP);
 			}
 
-			/* then reset the in-memory entry */
+			/* then clear the in-memory slot */
 			state->roident = InvalidRepOriginId;
 			state->remote_lsn = InvalidXLogRecPtr;
 			state->local_lsn = InvalidXLogRecPtr;
@@ -390,7 +403,11 @@ restart:
 		}
 	}
 	LWLockRelease(ReplicationOriginLock);
+	ConditionVariableCancelSleep();
 
+	/*
+	 * Now, we can delete the catalog entry.
+	 */
 	tuple = SearchSysCache1(REPLORIGIDENT, ObjectIdGetDatum(roident));
 	if (!HeapTupleIsValid(tuple))
 		elog(ERROR, "cache lookup failed for replication origin with oid %u",