diff --git a/src/librtlsdr.c b/src/librtlsdr.c
index 9b7ba52..e2c3c73 100644
--- a/src/librtlsdr.c
+++ b/src/librtlsdr.c
@@ -570,7 +570,7 @@ void rtlsdr_set_gpio_output(rtlsdr_dev_t *dev, uint8_t gpio)
 	gpio = 1 << gpio;
 
 	r = rtlsdr_read_reg(dev, SYSB, GPD, 1);
-	rtlsdr_write_reg(dev, SYSB, GPO, r & ~gpio, 1);
+	rtlsdr_write_reg(dev, SYSB, GPD, r & ~gpio, 1);
 	r = rtlsdr_read_reg(dev, SYSB, GPOE, 1);
 	rtlsdr_write_reg(dev, SYSB, GPOE, r | gpio, 1);
 }