diff --git a/zephcore/Kconfig b/zephcore/Kconfig
index 14110e8..388a40b 100644
--- a/zephcore/Kconfig
+++ b/zephcore/Kconfig
@@ -766,6 +766,7 @@ config ZEPHCORE_REPEATER_GPS_INTERVAL_SEC
 
 config ZEPHCORE_GPS_NMEA_DUMP
 	bool "Log every NMEA sentence received from the GNSS module"
+	depends on GNSS
 	help
 	  Print each sentence the GNSS driver parses, plus everything else the
 	  module emits, to the console. For diagnosing a receiver that reports
@@ -799,6 +800,12 @@ config ZEPHCORE_GPS_NAV_MODE
 
 config ZEPHCORE_GPS_SAT_DIAG
 	bool "GPS per-constellation satellite diagnostics"
+	# Must depend on GNSS, not just select GNSS_SATELLITES: on a board with
+	# no GNSS at all (native Linux, xiao_nrf52840) GNSS is n, and y-selecting
+	# a symbol whose dependencies are unmet is a Kconfig error that aborts the
+	# build — not a warning. The repeater default below would otherwise turn
+	# this on for every GNSS-less repeater target.
+	depends on GNSS
 	select GNSS_SATELLITES
 	default y if ZEPHCORE_ROLE_REPEATER
 	help
diff --git a/zephcore/adapters/gps/ZephyrGPSManager.cpp b/zephcore/adapters/gps/ZephyrGPSManager.cpp
index 6c49fcf..33dd3d9 100644
--- a/zephcore/adapters/gps/ZephyrGPSManager.cpp
+++ b/zephcore/adapters/gps/ZephyrGPSManager.cpp
@@ -29,6 +29,7 @@
 #include <zephyr/drivers/i2c.h>
 #include <zephyr/pm/device.h>
 #include <string.h>
+#include <stdio.h>
 #if defined(CONFIG_SOC_NRF52840)
 #include <nrfx.h>
 #endif
@@ -82,6 +83,12 @@ LOG_MODULE_REGISTER(zephcore_gps, CONFIG_ZEPHCORE_GPS_LOG_LEVEL);
 #define HAS_GPS_POWER_REGULATOR 0
 #endif
 
+/* Runtime diagnostics toggle. Declared OUT here, not inside the HAS_GNSS
+ * block: gps_set_diag()/gps_get_diag()/gps_get_diag_report() are part of the
+ * unconditional public API and are compiled on boards with no GNSS at all,
+ * so a declaration hidden behind HAS_GNSS breaks every such board. */
+static bool gps_diag_on = false;
+
 /* ========== GPS Power Strategy ==========
  * Module power is GPIO/regulator controlled — GNSS driver PM is not used
  * for the module itself:
@@ -482,7 +489,6 @@ static struct {
 	int64_t at_ms;       /* uptime when configuration last ran */
 } gps_cfg_diag;
 
-static bool gps_diag_on = false;
 
 /* Module identification string, captured by the GNSS driver from the reply to
  * its version query (CASIC parts answer in-band as a $GPTXT sentence).