diff --git a/lib/libc/gen/fstab.c b/lib/libc/gen/fstab.c
index 1351a27ccc73..b68db2effb6d 100644
--- a/lib/libc/gen/fstab.c
+++ b/lib/libc/gen/fstab.c
@@ -150,16 +150,18 @@ fstabscan(void)
 /* OLD_STYLE_FSTAB */
 		while ((cp = strsep(&p, " \t\n")) != NULL && *cp == '\0')
 			;
-		if (strunvis(cp, cp) < 0)
-			goto bad;
 		_fs_fstab.fs_spec = cp;
-		if (!_fs_fstab.fs_spec || *_fs_fstab.fs_spec == '#')
+		if (_fs_fstab.fs_spec == NULL || *_fs_fstab.fs_spec == '#')
 			continue;
+		if (strunvis(_fs_fstab.fs_spec, _fs_fstab.fs_spec) < 0)
+			goto bad;
 		while ((cp = strsep(&p, " \t\n")) != NULL && *cp == '\0')
 			;
-		if (strunvis(cp, cp) < 0)
-			goto bad;
 		_fs_fstab.fs_file = cp;
+		if (_fs_fstab.fs_file == NULL)
+			goto bad;
+		if (strunvis(_fs_fstab.fs_file, _fs_fstab.fs_file) < 0)
+			goto bad;
 		fixfsfile();
 		while ((cp = strsep(&p, " \t\n")) != NULL && *cp == '\0')
 			;