Index: uspace/srv/fs/fat/fat_dentry.c
===================================================================
--- uspace/srv/fs/fat/fat_dentry.c	(revision b6913b7a680d8a82aa53cc8eaf2b9a5df83eac1a)
+++ uspace/srv/fs/fat/fat_dentry.c	(revision a1d7b4b64d80fd99178eff41903b8d4810473657)
@@ -334,5 +334,5 @@
 	while (i < count) {
 		if ((ch = str_decode(src, &off, STR_NO_LIMIT)) != 0) {
-			if (ascii_check(ch) & IS_D_CHAR(ch))
+			if (ascii_check(ch) && IS_D_CHAR(ch))
 				*dst = toupper(ch);
 			else