diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 1a67725ec0..cb1bdc958d 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -101,7 +101,11 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	 * If 'endpoint' didn't point exactly at a record boundary, the caller
 	 * messed up.
 	 */
-	Assert(xlogreader->EndRecPtr == endpoint);
+	if (xlogreader->EndRecPtr != endpoint)
+		pg_fatal("end pointer %X/%X is not a valid end point; expected %X/%X",
+				 (uint32) (endpoint >> 32), (uint32) (endpoint),
+				 (uint32) (xlogreader->EndRecPtr >> 32), (uint32)
+				 (xlogreader->EndRecPtr));
 
 	XLogReaderFree(xlogreader);
 	if (xlogreadfd != -1)