diff --git a/src/asus.c b/src/asus.c
index ce44cc2b..cc279a1e 100644
--- a/src/asus.c
+++ b/src/asus.c
@@ -113,10 +113,11 @@ asus_find_key_code(unsigned int linux_code)
 	return -1;
 }
 
-/* convert ASUS key code to Linux key code */
 int
 asus_get_linux_key_code(uint8_t asus_code) {
-	assert(asus_code <= ARRAY_LENGTH(ASUS_KEY_MAPPING));
+	if (asus_code > ARRAY_LENGTH(ASUS_KEY_MAPPING)) {
+		return -1;
+	}
 	return ASUS_KEY_MAPPING[asus_code];
 }
 
diff --git a/src/asus.h b/src/asus.h
index 81ce2a45..95c0d643 100644
--- a/src/asus.h
+++ b/src/asus.h
@@ -164,6 +164,11 @@ asus_find_button_by_code(uint8_t asus_code);
 int
 asus_find_key_code(unsigned int linux_code);
 
+/*
+ * @param asus_code ASUS key code.
+ * @return Linux key code (as defined defined in linux/input-event-codes.h) or
+ * -1 on error.
+ */
 int
 asus_get_linux_key_code(uint8_t asus_code);
 
diff --git a/src/driver-asus.c b/src/driver-asus.c
index 1b28eee7..3f3cfe1b 100644
--- a/src/driver-asus.c
+++ b/src/driver-asus.c
@@ -22,7 +22,6 @@
  */
 
 #include "config.h"
-#include <assert.h>
 #include <errno.h>
 #include <libevdev/libevdev.h>
 #include <linux/input.h>
@@ -116,8 +115,12 @@ asus_driver_load_profile(struct ratbag_device *device, struct ratbag_profile *pr
 		switch (asus_binding->type) {
 		case ASUS_BUTTON_ACTION_TYPE_KEY:
 			button->action.type = RATBAG_BUTTON_ACTION_TYPE_KEY;
-			/* ASUS code to Linux code */
-			button->action.action.key.key = asus_get_linux_key_code(asus_binding->action);
+			rc = asus_get_linux_key_code(asus_binding->action);
+			if (rc > 0) {
+				button->action.action.key.key = (unsigned int)rc;
+			} else {
+				log_debug(device->ratbag, "Unknown button code %02x\n", asus_binding->action);
+			}
 			break;
 
 		case ASUS_BUTTON_ACTION_TYPE_BUTTON: