diff --git a/src/bin/pg_basebackup/walmethods.c b/src/bin/pg_basebackup/walmethods.c
index e90aa0ba37..edddd9b578 100644
--- a/src/bin/pg_basebackup/walmethods.c
+++ b/src/bin/pg_basebackup/walmethods.c
@@ -1358,7 +1358,7 @@ CreateWalTarMethod(const char *tarbase,
 	sprintf(tar_data->tarfilename, "%s%s", tarbase, suffix);
 	tar_data->fd = -1;
 	tar_data->compression_algorithm = compression_algorithm;
-	tar_data->compression_level = compression_level;
+	tar_data->compression_level = compression_level > 0 ? compression_level : Z_DEFAULT_COMPRESSION;
 	tar_data->sync = sync;
 #ifdef HAVE_LIBZ
 	if (compression_algorithm == PG_COMPRESSION_GZIP)