diff --git a/bin/pgut/pgut.c b/bin/pgut/pgut.c
index 3261ac4..90ed8cb 100644
--- a/bin/pgut/pgut.c
+++ b/bin/pgut/pgut.c
@@ -1307,7 +1307,7 @@ pgut_malloc(size_t size)
 	if ((ret = malloc(size)) == NULL)
 		ereport(FATAL,
 			(errcode_errno(),
-			 errmsg("could not allocate memory (%lu bytes): ",
+			 errmsg("could not allocate memory (" UINT64_FORMAT " bytes): ",
 				(unsigned long) size)));
 	return ret;
 }
@@ -1320,7 +1320,7 @@ pgut_realloc(void *p, size_t size)
 	if ((ret = realloc(p, size)) == NULL)
 		ereport(FATAL,
 			(errcode_errno(),
-			 errmsg("could not re-allocate memory (%lu bytes): ",
+			 errmsg("could not re-allocate memory (" UINT64_FORMAT " bytes): ",
 				(unsigned long) size)));
 	return ret;
 }
diff --git a/lib/repack.c b/lib/repack.c
index a5405af..22a6b56 100644
--- a/lib/repack.c
+++ b/lib/repack.c
@@ -1306,7 +1306,7 @@ repack_index_swap(PG_FUNCTION_ARGS)
 					 orig_idx_oid);
 	execute(SPI_OK_SELECT, str.data);
 	if (SPI_processed != 1)
-		elog(ERROR, "Could not find index 'index_%u', found %lu matches",
+		elog(ERROR, "Could not find index 'index_%u', found " UINT64_FORMAT " matches",
 			 orig_idx_oid, (uint64) SPI_processed);
 
 	tuptable = SPI_tuptable;