--- src/VBox/Devices/Audio/DevIchAc97.cpp.orig	2009-12-16 09:13:05.930459951 +0800
+++ src/VBox/Devices/Audio/DevIchAc97.cpp	2009-12-16 09:18:13.404715106 +0800
@@ -490,23 +490,8 @@
 static void set_volume (AC97LinkState *s, int index,
                         audmixerctl_t mt, uint32_t val)
 {
-    int mute = (val >> MUTE_SHIFT) & 1;
-    uint8_t rvol = VOL_MASK - (val & VOL_MASK);
-    uint8_t lvol = VOL_MASK - ((val >> 8) & VOL_MASK);
-    rvol = 255 * rvol / VOL_MASK;
-    lvol = 255 * lvol / VOL_MASK;
-
-# ifdef SOFT_VOLUME
-    if (index == AC97_Master_Volume_Mute)
-        AUD_set_volume_out (s->voice_po, mute, lvol, rvol);
-    else
-        AUD_set_volume (mt, &mute, &lvol, &rvol);
-# else
-    AUD_set_volume (mt, &mute, &lvol, &rvol);
-# endif
-
-    rvol = VOL_MASK - ((VOL_MASK * rvol) / 255);
-    lvol = VOL_MASK - ((VOL_MASK * lvol) / 255);
+    int mute;
+    uint8_t rvol, lvol;
 
     /*
      * From AC'97 SoundMax Codec AD1981A: "Because AC '97 defines 6-bit volume registers, to
@@ -521,6 +506,24 @@
     if (val & RT_BIT(13))
         val |= RT_BIT(12) | RT_BIT(11) | RT_BIT(10) | RT_BIT(9) | RT_BIT(8);
 
+    /*
+     * 5-bit volume, behave like one.
+     */
+    val &= ~(RT_BIT(5) | RT_BIT(13));
+
+    mute = (val >> MUTE_SHIFT) & 1;
+    rvol = (255 * (VOL_MASK - (val & VOL_MASK))) / VOL_MASK;
+    lvol = (255 * (VOL_MASK - ((val >> 8) & VOL_MASK))) / VOL_MASK;
+
+# ifdef SOFT_VOLUME
+    if (index == AC97_Master_Volume_Mute)
+        AUD_set_volume_out (s->voice_po, mute, lvol, rvol);
+    else
+        AUD_set_volume (mt, &mute, &lvol, &rvol);
+# else
+    AUD_set_volume (mt, &mute, &lvol, &rvol);
+# endif
+
     mixer_store (s, index, val);
 }