diff --git a/pca9685.go b/pca9685.go
index abc2e8f..60f513f 100644
--- a/pca9685.go
+++ b/pca9685.go
@@ -182,10 +182,10 @@ func (p *PCA9685) setPwm(pwm int, on uint16, off uint16) {
 	onB := byte(on)
 	offB := byte(off)
 
-	p.i2cBus.WriteReg(LED0_ON_L+byte(4)*byte(pwm), []byte{onB & WORD})
-	p.i2cBus.WriteReg(LED0_ON_H+byte(4)*byte(pwm), []byte{onB >> 8})
-	p.i2cBus.WriteReg(LED0_OFF_L+byte(4)*byte(pwm), []byte{offB & WORD})
-	p.i2cBus.WriteReg(LED0_OFF_H+byte(4)*byte(pwm), []byte{offB >> 8})
+	p.i2cBus.WriteReg(LED0_ON_L+byte(4)*byte(pwm), []byte{onB & 0xF0})
+	p.i2cBus.WriteReg(LED0_ON_H+byte(4)*byte(pwm), []byte{onB & 0x0F})
+	p.i2cBus.WriteReg(LED0_OFF_L+byte(4)*byte(pwm), []byte{offB & 0xF0})
+	p.i2cBus.WriteReg(LED0_OFF_H+byte(4)*byte(pwm), []byte{offB & 0x0F})
 }
 
 func (pwm *Pwm) setPercentage(percentage float32) error {