diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 9568ff1..af2486e 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -2800,6 +2800,7 @@ void
 TruncateMultiXact(void)
 {
 	MultiXactId oldestMXact;
+	MultiXactId nextMultiXactId;
 	MultiXactOffset oldestOffset;
 	MultiXactOffset nextOffset;
 	mxtruncinfo trunc;
@@ -2811,9 +2812,14 @@ TruncateMultiXact(void)
 
 	LWLockAcquire(MultiXactGenLock, LW_SHARED);
 	oldestMXact = MultiXactState->lastCheckpointedOldest;
+	nextMultiXactId = MultiXactState->nextMXact;
 	LWLockRelease(MultiXactGenLock);
 	Assert(MultiXactIdIsValid(oldestMXact));
 
+	/* If there are no multixacts, there is nothing to do. */
+	if (nextMultiXactId == oldestMXact)
+		return;
+
 	/*
 	 * Note we can't just plow ahead with the truncation; it's possible that
 	 * there are no segments to truncate, which is a problem because we are