diff --git a/src/input.h b/src/input.h
index 825904a..f1fdf72 100644
--- a/src/input.h
+++ b/src/input.h
@@ -54,11 +54,13 @@
 
 struct kmscon_input;
 
+#define KMSCON_INPUT_INVALID 0xffffffff
+
 struct kmscon_input_event {
 	uint16_t keycode;  /* linux keycode - KEY_* - linux/input.h */
 	uint32_t keysym;   /* X keysym - XK_* - X11/keysym.h */
 	uint8_t modifiers; /* xkbcommon modifiers - XKB_COMMON_*_MASK */
-	uint32_t unicode;  /* UCS-4 unicode value, 0 if none */
+	uint32_t unicode;  /* UCS-4 unicode value or KMSCON_INPUT_INVALID */
 };
 
 typedef void (*kmscon_input_cb) (struct kmscon_input *input,
diff --git a/src/input_xkb.c b/src/input_xkb.c
index 9eddc31..8a28c4a 100644
--- a/src/input_xkb.c
+++ b/src/input_xkb.c
@@ -704,6 +704,9 @@ bool kmscon_xkb_process_evdev_key(struct xkb_desc *desc,
 		out->modifiers = state->mods;
 		out->unicode = KeysymToUcs4(sym);
 
+		if (out->unicode == 0)
+			out->unicode = KMSCON_INPUT_INVALID;
+
 		event_filled = true;
 	}
 
diff --git a/tests/test_input.c b/tests/test_input.c
index f5523ac..3bda398 100644
--- a/tests/test_input.c
+++ b/tests/test_input.c
@@ -90,7 +90,7 @@ static void input_arrived(struct kmscon_input *input,
 	char s[16];
 	char utf8[MB_CUR_MAX + 1];
 
-	if (ev->unicode == 0) {
+	if (ev->unicode == KMSCON_INPUT_INVALID) {
 		xkb_keysym_to_string(ev->keysym, s, sizeof(s));
 		printf("sym %s ", s);
 	} else {