diff --git a/linux_mtd.c b/linux_mtd.c
index d5fc5094f..b1d0255de 100644
--- a/linux_mtd.c
+++ b/linux_mtd.c
@@ -49,7 +49,7 @@ static int read_sysfs_string(const char *sysfs_path, const char *filename, char
 	int i;
 	size_t bytes_read;
 	FILE *fp;
-	char path[strlen(LINUX_MTD_SYSFS_ROOT) + 32];
+	char path[sizeof(LINUX_MTD_SYSFS_ROOT) + 31];
 
 	snprintf(path, sizeof(path), "%s/%s", sysfs_path, filename);