diff --git a/README.md b/README.md
index 27a4a10..93b7b12 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,16 @@ If you use any other status bar or window manager you will have to figure it out
 
 	slstatus -o | other_status_bar &
 
+### Specific function quirks
+
+- Volume percentage
+
+If there is no `/dev/mixer` on your system and you use ALSA, it means you have to load the OSS compatibility module by issuing:
+
+```
+# modprobe snd-pcm-oss
+```
+
 ## Contributing
 
 Hunt FIXME's in the code or do WTF you want! If it is useful, I will merge.
diff --git a/config.def.h b/config.def.h
index 4ce5958..caddd7f 100644
--- a/config.def.h
+++ b/config.def.h
@@ -34,7 +34,7 @@
 - uid (uid of current user) [argument: NULL]
 - uptime (uptime) [argument: NULL]
 - username (username of current user) [argument: NULL]
-- vol_perc (oss/alsa volume and mute status in percent) [argument: /dev/mixer]
+- vol_perc (oss/alsa volume status (see README)) [argument: /dev/mixer]
 - wifi_perc (wifi signal in percent) [argument: wifi card interface name]
 - wifi_essid (wifi essid) [argument: wifi card interface name] */
 static const struct arg args[] = {
diff --git a/slstatus.c b/slstatus.c
index d580ac0..ff81e0c 100644
--- a/slstatus.c
+++ b/slstatus.c
@@ -628,14 +628,18 @@ vol_perc(const char *card)
 	}
 
 	ioctl(afd, MIXER_READ(SOUND_MIXER_DEVMASK), &devmask);
-	for (i = 0; i < (sizeof(vnames) / sizeof((vnames[0]))); i++)
-		if (devmask & (1 << i))
-			if (!strcmp("vol", vnames[i]))
+	for (i = 0; i < (sizeof(vnames) / sizeof((vnames[0]))); i++) {
+		if (devmask & (1 << i)) {
+			if (!strcmp("vol", vnames[i])) {
 				ioctl(afd, MIXER_READ(i), &v);
+			}
+		}
+	}
 
 	close(afd);
-	if (v == 0)
+	if (v == 0) {
 		return smprintf("mute");
+	}
 	return smprintf("%d%%", v & 0xff);
 }