diff --git a/firmware/common/sgpio.c b/firmware/common/sgpio.c
index c0da0fe6..41baa00f 100644
--- a/firmware/common/sgpio.c
+++ b/firmware/common/sgpio.c
@@ -48,7 +48,7 @@ void sgpio_configure_pin_functions() {
 	scu_pinmux(SCU_PINMUX_SGPIO14, SCU_GPIO_FAST | SCU_CONF_FUNCTION4);	/* GPIO5[13] */
 	scu_pinmux(SCU_PINMUX_SGPIO15, SCU_GPIO_FAST | SCU_CONF_FUNCTION4);	/* GPIO5[14] */
 
-	sgpio_cpld_stream_rx_set_decimation(0);
+	sgpio_cpld_stream_rx_set_decimation(1);
 
 	GPIO_DIR(GPIO5) |= GPIOPIN14 | GPIOPIN13 | GPIOPIN12;
 }
@@ -286,7 +286,7 @@ bool sgpio_cpld_stream_is_enabled() {
 	return (SGPIO_GPIO_OUTREG & (1L << 10)) == 0; /* SGPIO10 */
 }
 
-bool sgpio_cpld_stream_rx_set_decimation(const uint_fast8_t skip_n) {
+bool sgpio_cpld_stream_rx_set_decimation(const uint_fast8_t n) {
 	/* CPLD interface is three bits, SGPIO[15:13]:
 	 * 111: decimate by 1 (skip_n=0, skip no samples)
 	 * 110: decimate by 2 (skip_n=1, skip every other sample)
@@ -294,6 +294,7 @@ bool sgpio_cpld_stream_rx_set_decimation(const uint_fast8_t skip_n) {
 	 * ...
 	 * 000: decimate by 8 (skip_n=7, skip seven of eight samples)
 	 */
+	const uint_fast8_t skip_n = n - 1;
 	GPIO_SET(GPIO5) = GPIOPIN14 | GPIOPIN13 | GPIOPIN12;
 	GPIO_CLR(GPIO5) = (skip_n & 7) << 12;
 
diff --git a/firmware/common/sgpio.h b/firmware/common/sgpio.h
index 8f0bb125..62bc8f4e 100644
--- a/firmware/common/sgpio.h
+++ b/firmware/common/sgpio.h
@@ -41,6 +41,6 @@ void sgpio_cpld_stream_enable();
 void sgpio_cpld_stream_disable();
 bool sgpio_cpld_stream_is_enabled();
 
-bool sgpio_cpld_stream_rx_set_decimation(const uint_fast8_t skip_n);
+bool sgpio_cpld_stream_rx_set_decimation(const uint_fast8_t n);
 
 #endif//__SGPIO_H__