diff --git a/sound/core/init.c b/sound/core/init.c
index 3f08104e9366..f142e73e2e3f 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -673,13 +673,19 @@ int snd_card_free(struct snd_card *card)
 }
 EXPORT_SYMBOL(snd_card_free);
 
+/* check, if the character is in the valid ASCII range */
+static inline bool safe_ascii_char(char c)
+{
+	return isascii(c) && isalnum(c);
+}
+
 /* retrieve the last word of shortname or longname */
 static const char *retrieve_id_from_card_name(const char *name)
 {
 	const char *spos = name;
 
 	while (*name) {
-		if (isspace(*name) && isalnum(name[1]))
+		if (isspace(*name) && safe_ascii_char(name[1]))
 			spos = name + 1;
 		name++;
 	}
@@ -706,12 +712,12 @@ static void copy_valid_id_string(struct snd_card *card, const char *src,
 {
 	char *id = card->id;
 
-	while (*nid && !isalnum(*nid))
+	while (*nid && !safe_ascii_char(*nid))
 		nid++;
 	if (isdigit(*nid))
 		*id++ = isalpha(*src) ? *src : 'D';
 	while (*nid && (size_t)(id - card->id) < sizeof(card->id) - 1) {
-		if (isalnum(*nid))
+		if (safe_ascii_char(*nid))
 			*id++ = *nid;
 		nid++;
 	}
@@ -807,7 +813,7 @@ static ssize_t id_store(struct device *dev, struct device_attribute *attr,
 
 	for (idx = 0; idx < copy; idx++) {
 		c = buf[idx];
-		if (!isalnum(c) && c != '_' && c != '-')
+		if (!safe_ascii_char(c) && c != '_' && c != '-')
 			return -EINVAL;
 	}
 	memcpy(buf1, buf, copy);