diff --git a/Sources/Controllers/ISSoundAdditions.m b/Sources/Controllers/ISSoundAdditions.m
index 4f2297f..e9094b3 100755
--- a/Sources/Controllers/ISSoundAdditions.m
+++ b/Sources/Controllers/ISSoundAdditions.m
@@ -129,7 +129,7 @@ + (void)setSystemVolume:(float)theVolume
 	}
 	
 		//check if the new value is in the correct range - normalize it if not
-	newValue = theVolume > 1.0 ? 1.0 : (theVolume < 0.0 ? 0.0 : theVolume);
+	newValue = theVolume > 1.0 ? 1.0 : (theVolume <= 0.0 ? 0.0 : theVolume);
 	if (newValue != theVolume) {
 		NSLog(@"Tentative volume (%5.2f) was out of range; reset to %5.2f", theVolume, newValue);
 	}
@@ -138,7 +138,7 @@ + (void)setSystemVolume:(float)theVolume
 	theAddress.mScope = kAudioDevicePropertyScopeOutput;
 	
 		//set the selector to mute or not by checking if under threshold and check if a mute command is available
-	if ( (muteValue = (newValue < THRESHOLD)) )
+	if ( (muteValue = (newValue <= THRESHOLD)) )
 	{
 		theAddress.mSelector = kAudioDevicePropertyMute;
 		hasMute = AudioObjectHasProperty(defaultDevID, &theAddress);