diff --git a/firmware/application/clock_manager.cpp b/firmware/application/clock_manager.cpp
index fdd41b01..86682b74 100644
--- a/firmware/application/clock_manager.cpp
+++ b/firmware/application/clock_manager.cpp
@@ -163,24 +163,16 @@ constexpr si5351::MultisynthFractional si5351_ms_10m {
 };
 constexpr auto si5351_ms_3_10m_reg = si5351_ms_10m.reg(3);
 
-constexpr si5351::MultisynthFractional si5351_ms_50m {
+constexpr si5351::MultisynthFractional si5351_ms_40m {
 	.f_src = si5351_vco_f,
-	.a = 16,
+	.a = 20,
 	.b = 0,
 	.c = 1,
 	.r_div = 0,
 };
 
-// constexpr si5351::MultisynthFractional si5351_ms_40m {
-// 	.f_src = si5351_vco_f,
-// 	.a = 20,
-// 	.b = 0,
-// 	.c = 1,
-// 	.r_div = 0,
-// };
-
-constexpr auto si5351_ms_rffc5072 = si5351_ms_50m;
-constexpr auto si5351_ms_max2837 = si5351_ms_50m;
+constexpr auto si5351_ms_rffc5072 = si5351_ms_40m;
+constexpr auto si5351_ms_max2837 = si5351_ms_40m;
 
 constexpr auto si5351_ms_4_reg = si5351_ms_rffc5072.reg(clock_generator_output_first_if);
 constexpr auto si5351_ms_5_reg = si5351_ms_max2837.reg(clock_generator_output_second_if);
diff --git a/firmware/common/hackrf_hal.hpp b/firmware/common/hackrf_hal.hpp
index 4c25c3ea..8b41f0a3 100644
--- a/firmware/common/hackrf_hal.hpp
+++ b/firmware/common/hackrf_hal.hpp
@@ -49,8 +49,8 @@ constexpr ClockFrequency ssp1_pclk_f		= base_m4_clk_f;
 constexpr ClockFrequency max5864_spi_f		= 20000000U;
 constexpr ClockFrequency max2837_spi_f 		= 20000000U;
 
-constexpr ClockFrequency rffc5072_reference_f	= 50000000U;
-constexpr ClockFrequency max2837_reference_f	= 50000000U;
+constexpr ClockFrequency rffc5072_reference_f	= 40000000U;
+constexpr ClockFrequency max2837_reference_f	= 40000000U;
 constexpr ClockFrequency mcu_clkin_f			= 40000000U;
 
 constexpr uint8_t si5351_i2c_address = 0x60;