diff --git a/external/bsd/libarchive/dist/tar/write.c b/external/bsd/libarchive/dist/tar/write.c
index 1c4fcb43b6a4..9c813992992b 100644
--- a/external/bsd/libarchive/dist/tar/write.c
+++ b/external/bsd/libarchive/dist/tar/write.c
@@ -798,7 +798,9 @@ copy_file_data_block(struct bsdtar *bsdtar, struct archive *a,
 		progress += bytes_written;
 	}
 	if (r < ARCHIVE_WARN) {
-		lafe_warnc(archive_errno(a), "%s", archive_error_string(a));
+		const char *s = archive_error_string(a);
+		if (s)
+			lafe_warnc(archive_errno(a), "%s", s);
 		return (-1);
 	}
 	return (0);