diff --git a/ratbagd/ratbagd-button.c b/ratbagd/ratbagd-button.c
index 7f5f9bd0..85060260 100644
--- a/ratbagd/ratbagd-button.c
+++ b/ratbagd/ratbagd-button.c
@@ -58,6 +58,8 @@ static int ratbagd_button_get_type(sd_bus *bus,
 
 	t = ratbag_button_get_type(button->lib_button);
 
+	verify_unsigned_int(t);
+
 	return sd_bus_message_append(reply, "u", t);
 }
 
@@ -74,6 +76,8 @@ static int ratbagd_button_get_button(sd_bus *bus,
 
 	b = ratbag_button_get_button(button->lib_button);
 
+	verify_unsigned_int(b);
+
 	return sd_bus_message_append(reply, "u", b);
 }
 
@@ -134,6 +138,8 @@ static int ratbagd_button_get_special(sd_bus *bus,
 		special = RATBAG_BUTTON_ACTION_SPECIAL_UNKNOWN;
 	}
 
+	verify_unsigned_int(special);
+
 	return sd_bus_message_append(reply, "u", special);
 }
 
@@ -218,6 +224,9 @@ static int ratbagd_button_get_macro(sd_bus *bus,
 			abort();
 		}
 
+		verify_unsigned_int(type);
+		verify_unsigned_int(value);
+
 		r = sd_bus_message_append(reply, "(uu)", type, value);
 		if (r < 0)
 			return r;
@@ -300,6 +309,8 @@ static int ratbagd_button_get_action_type(sd_bus *bus,
 	if (type == RATBAG_BUTTON_ACTION_TYPE_KEY)
 		type = RATBAG_BUTTON_ACTION_TYPE_UNKNOWN;
 
+	verify_unsigned_int(type);
+
 	return sd_bus_message_append(reply, "u", type);
 }
 
@@ -329,6 +340,7 @@ static int ratbagd_button_get_action_types(sd_bus *bus,
 		if (!ratbag_button_has_action_type(button->lib_button, *t))
 			continue;
 
+		verify_unsigned_int(*t);
 		r = sd_bus_message_append(reply, "u", *t);
 		if (r < 0)
 			return r;
diff --git a/ratbagd/ratbagd-led.c b/ratbagd/ratbagd-led.c
index e3b4b39c..de8ea2ba 100644
--- a/ratbagd/ratbagd-led.c
+++ b/ratbagd/ratbagd-led.c
@@ -78,6 +78,9 @@ static int ratbagd_led_get_mode(sd_bus *bus,
 	enum ratbag_led_mode mode;
 
 	mode = ratbag_led_get_mode(led->lib_led);
+
+	verify_unsigned_int(mode);
+
 	return sd_bus_message_append(reply, "u", mode);
 }
 
@@ -124,6 +127,8 @@ static int ratbagd_led_get_type(sd_bus *bus,
 
 	type = ratbag_led_get_type(led->lib_led);
 
+	verify_unsigned_int(type);
+
 	return sd_bus_message_append(reply, "u", type);
 }
 
@@ -191,6 +196,9 @@ static int ratbagd_led_get_effect_duration(sd_bus *bus,
 	int rate;
 
 	rate = ratbag_led_get_effect_duration(led->lib_led);
+
+	verify_unsigned_int(rate);
+
 	return sd_bus_message_append(reply, "u", rate);
 }
 
@@ -239,6 +247,9 @@ static int ratbagd_led_get_brightness(sd_bus *bus,
 	unsigned int brightness;
 
 	brightness = ratbag_led_get_brightness(led->lib_led);
+
+	verify_unsigned_int(brightness);
+
 	return sd_bus_message_append(reply, "u", brightness);
 }
 
diff --git a/ratbagd/ratbagd-resolution.c b/ratbagd/ratbagd-resolution.c
index 70322a50..48fd7234 100644
--- a/ratbagd/ratbagd-resolution.c
+++ b/ratbagd/ratbagd-resolution.c
@@ -214,6 +214,7 @@ ratbagd_resolution_get_resolutions(sd_bus *bus,
 	assert(ndpis <= ARRAY_LENGTH(dpis));
 
 	for (unsigned int i = 0; i < ndpis; i++) {
+		verify_unsigned_int(dpis[i]);
 		r = sd_bus_message_append(reply, "u", dpis[i]);
 		if (r < 0)
 			return r;
@@ -238,6 +239,9 @@ ratbagd_resolution_get_resolution(sd_bus *bus,
 	xres = ratbag_resolution_get_dpi_x(lib_resolution);
 	yres = ratbag_resolution_get_dpi_y(lib_resolution);
 
+	verify_unsigned_int(xres);
+	verify_unsigned_int(yres);
+
 	return sd_bus_message_append(reply, "(uu)", xres, yres);
 }
 
@@ -293,6 +297,7 @@ ratbagd_resolution_get_report_rate(sd_bus *bus,
 	int rate;
 
 	rate = ratbag_resolution_get_report_rate(lib_resolution);
+	verify_unsigned_int(rate);
 	return sd_bus_message_append(reply, "u", rate);
 }
 
@@ -320,6 +325,7 @@ ratbagd_resolution_get_report_rates(sd_bus *bus,
 	assert(nrates <= ARRAY_LENGTH(rates));
 
 	for (unsigned int i = 0; i < nrates; i++) {
+		verify_unsigned_int(rates[i]);
 		r = sd_bus_message_append(reply, "u", rates[i]);
 		if (r < 0)
 			return r;
diff --git a/ratbagd/ratbagd.h b/ratbagd/ratbagd.h
index 20434fcf..28b7d643 100644
--- a/ratbagd/ratbagd.h
+++ b/ratbagd/ratbagd.h
@@ -176,6 +176,19 @@ struct ratbagd_device *ratbagd_device_next(struct ratbagd_device *device);
 	     (_device);						\
 	     _device = (_safe),				\
 	     _safe = (_safe) ? ratbagd_device_next(_safe) : NULL)
+
+/* Verify that _val is not -1. This traps DBus API errors where we end up
+ * sending a valid-looking index across and then fail on the other side.
+ *
+ * do {} while(0) so we can terminate with a ; without the compiler
+ * complaining about an empty statement;
+ * */
+#define verify_unsigned_int(_val) \
+	do { if ((int)_val == -1) { \
+		log_error("%s:%d - %s: expected unsigned int, got -1\n", __FILE__, __LINE__, __func__); \
+		return -EINVAL; \
+	} } while(0)
+
 /*
  * Context
  */