diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h
index 9fc429d2852d..a77b74c5fb65 100644
--- a/tools/lib/api/io.h
+++ b/tools/lib/api/io.h
@@ -180,6 +180,7 @@ static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_l
 	return line_len;
 err_out:
 	free(line);
+	*line_out = NULL;
 	return -ENOMEM;
 }