diff --git a/src/include/storage/checksum_impl.h b/src/include/storage/checksum_impl.h
index 2f81cdf5b5..364acfafd2 100644
--- a/src/include/storage/checksum_impl.h
+++ b/src/include/storage/checksum_impl.h
@@ -211,5 +211,5 @@ pg_checksum_page(char *page, BlockNumber blkno)
 	 * Reduce to a uint16 (to fit in the pd_checksum field) with an offset of
 	 * one. That avoids checksums of zero, which seems like a good idea.
 	 */
-	return (uint16) ((checksum % 65536) + 1);
+	return (uint16) ((checksum % 65535) + 1);
 }