diff --git a/dist/hornverifier b/dist/hornverifier
index cd817e12..6874b926 100755
Binary files a/dist/hornverifier and b/dist/hornverifier differ
diff --git a/dist/roverd b/dist/roverd
index fa9c07ba..34c8d280 100755
Binary files a/dist/roverd and b/dist/roverd differ
diff --git a/dist/servoverifier b/dist/servoverifier
index f79f69e8..9fbf1cc1 100755
Binary files a/dist/servoverifier and b/dist/servoverifier differ
diff --git a/pi/roverd/audio_levels.go b/pi/roverd/audio_levels.go
index e92a2b7f..8716d2b5 100644
--- a/pi/roverd/audio_levels.go
+++ b/pi/roverd/audio_levels.go
@@ -85,9 +85,17 @@ func (c *WSClient) applyMixerGain(control string, gain float64) {
 		db = -60.0
 	}
 
-	dbArg := fmt.Sprintf("%.2fdB", db)
-	if err := c.trySetMixerControl(control, dbArg); err != nil {
-		c.log.Printf("audio-levels: amixer set %s=%s failed: %v", control, dbArg, err)
+	// amixer treats a leading "-" value as an option; set via percent to avoid getopt ambiguity.
+	percent := int(math.Round((db + 60.0) / 72.0 * 100.0))
+	if percent < 0 {
+		percent = 0
+	}
+	if percent > 100 {
+		percent = 100
+	}
+	percentArg := fmt.Sprintf("%d%%", percent)
+	if err := c.trySetMixerControl(control, percentArg); err != nil {
+		c.log.Printf("audio-levels: amixer set %s=%s failed: %v", control, percentArg, err)
 	}
 }