diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 32bbe11da3..879d80e187 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -943,7 +943,7 @@ static void WALInsertLockUpdateInsertingAt(XLogRecPtr insertingAt);
  *
  * If 'fpw_lsn' is valid, it is the oldest LSN among the pages that this
  * WAL record applies to, that were not included in the record as full page
- * images.  If fpw_lsn >= RedoRecPtr, the function does not perform the
+ * images.  If fpw_lsn <= RedoRecPtr, the function does not perform the
  * insertion and returns InvalidXLogRecPtr.  The caller can then recalculate
  * which pages need a full-page image, and retry.  If fpw_lsn is invalid, the
  * record is always inserted.
@@ -976,6 +976,7 @@ XLogInsertRecord(XLogRecData *rdata,
 							   info == XLOG_SWITCH);
 	XLogRecPtr	StartPos;
 	XLogRecPtr	EndPos;
+	bool		prevDoPageWrites = doPageWrites;
 
 	/* we assume that all of the record header is in the first chunk */
 	Assert(rdata->len >= SizeOfXLogRecord);
@@ -1023,10 +1024,14 @@ XLogInsertRecord(XLogRecData *rdata,
 		WALInsertLockAcquire();
 
 	/*
-	 * Check to see if my copy of RedoRecPtr or doPageWrites is out of date.
-	 * If so, may have to go back and have the caller recompute everything.
-	 * This can only happen just after a checkpoint, so it's better to be slow
-	 * in this case and fast otherwise.
+	 * Check to see if my copy of RedoRecPtr is out of date. If so, may have
+	 * to go back and have the caller recompute everything. This can only
+	 * happen just after a checkpoint, so it's better to be slow in this case
+	 * and fast otherwise.
+	 *
+	 * Also check to see if fullPageWrites or forcePageWrites was just turned
+	 * on; if we weren't already doing full-page writes then go back and
+	 * recompute.
 	 *
 	 * If we aren't doing full-page writes then RedoRecPtr doesn't actually
 	 * affect the contents of the XLOG record, so we'll update our local copy
@@ -1041,7 +1046,9 @@ XLogInsertRecord(XLogRecData *rdata,
 	}
 	doPageWrites = (Insert->fullPageWrites || Insert->forcePageWrites);
 
-	if (fpw_lsn != InvalidXLogRecPtr && fpw_lsn <= RedoRecPtr && doPageWrites)
+	if (doPageWrites &&
+		(!prevDoPageWrites ||
+		 (fpw_lsn != InvalidXLogRecPtr && fpw_lsn <= RedoRecPtr)))
 	{
 		/*
 		 * Oops, some buffer now needs to be backed up that the caller didn't