diff --git a/sdk/lib/drivers/sound/mmixer/midi.c b/sdk/lib/drivers/sound/mmixer/midi.c
index d659381de0b..969f252773a 100644
--- a/sdk/lib/drivers/sound/mmixer/midi.c
+++ b/sdk/lib/drivers/sound/mmixer/midi.c
@@ -72,7 +72,7 @@ MMixerAddMidiPin(
     MidiInfo->PinId = PinId;
 
     /* sanity check */
-    ASSERT(!DeviceName || (wcslen(DeviceName) + 1 < MAXPNAMELEN));
+    ASSERT(!DeviceName || (wcslen(DeviceName) < MAXPNAMELEN));
 
     /* copy device name */
     if (bInput && DeviceName)
diff --git a/sdk/lib/drivers/sound/mmixer/wave.c b/sdk/lib/drivers/sound/mmixer/wave.c
index 962934b8d5c..6326e3227d7 100644
--- a/sdk/lib/drivers/sound/mmixer/wave.c
+++ b/sdk/lib/drivers/sound/mmixer/wave.c
@@ -357,7 +357,7 @@ MMixerInitializeWaveInfo(
     WaveInfo->PinId = Pins[0];
 
     /* sanity check */
-    ASSERT(wcslen(DeviceName) + 1 < MAXPNAMELEN);
+    ASSERT(wcslen(DeviceName) < MAXPNAMELEN);
 
     /* copy device name */
     if (bWaveIn)