diff --git a/firmware/common/hackrf_core.c b/firmware/common/hackrf_core.c
index 1ee7e3e6..ca1c3389 100644
--- a/firmware/common/hackrf_core.c
+++ b/firmware/common/hackrf_core.c
@@ -716,7 +716,7 @@ void cpu_clock_init(void)
 #endif
 }
 
-void activate_best_clock_source(void)
+clock_source_t activate_best_clock_source(void)
 {
 #ifdef HACKRF_ONE
 	/* Ensure PortaPack reference oscillator is off while checking for external clock input. */
@@ -728,6 +728,7 @@ void activate_best_clock_source(void)
 	/* Check for external clock input. */
 	if (si5351c_clkin_signal_valid(&clock_gen)) {
 		si5351c_set_clock_source(&clock_gen, PLL_SOURCE_CLKIN);
+		return CLOCK_SOURCE_EXTERNAL;
 	} else {
 #ifdef HACKRF_ONE
 		/* Enable PortaPack reference oscillator (if present), and check for valid clock. */
@@ -736,7 +737,7 @@ void activate_best_clock_source(void)
 			delay(510000);	/* loop iterations @ 204MHz for >10ms for oscillator to enable. */
 			if (si5351c_clkin_signal_valid(&clock_gen)) {
 				si5351c_set_clock_source(&clock_gen, PLL_SOURCE_CLKIN);
-				return;
+				return CLOCK_SOURCE_PORTAPACK;
 			} else {
 				portapack_reference_oscillator(false);
 			}
@@ -744,6 +745,7 @@ void activate_best_clock_source(void)
 #endif
 		/* No external or PortaPack clock was found. Use HackRF Si5351C crystal. */
 		si5351c_set_clock_source(&clock_gen, PLL_SOURCE_XTAL);
+		return CLOCK_SOURCE_HACKRF;
 	}
 }
 
diff --git a/firmware/common/hackrf_core.h b/firmware/common/hackrf_core.h
index e6e4e811..912fa991 100644
--- a/firmware/common/hackrf_core.h
+++ b/firmware/common/hackrf_core.h
@@ -264,6 +264,12 @@ typedef enum {
 	HW_SYNC_MODE_ON = 1,
 } hw_sync_mode_t;
 
+typedef enum {
+	CLOCK_SOURCE_HACKRF = 0,
+	CLOCK_SOURCE_EXTERNAL = 1,
+	CLOCK_SOURCE_PORTAPACK = 2,
+} clock_source_t;
+
 void delay(uint32_t duration);
 
 /* TODO: Hide these configurations */
@@ -294,7 +300,7 @@ bool sample_rate_frac_set(uint32_t rate_num, uint32_t rate_denom);
 bool sample_rate_set(const uint32_t sampling_rate_hz);
 bool baseband_filter_bandwidth_set(const uint32_t bandwidth_hz);
 
-void activate_best_clock_source(void);
+clock_source_t activate_best_clock_source(void);
 
 #if (defined HACKRF_ONE || defined RAD1O)
 void enable_rf_power(void);