diff --git a/quantum/process_keycode/process_ucis.c b/quantum/process_keycode/process_ucis.c
index 91a038bab1cd..9417e1226370 100644
--- a/quantum/process_keycode/process_ucis.c
+++ b/quantum/process_keycode/process_ucis.c
@@ -36,6 +36,8 @@ bool process_ucis(uint16_t keycode, keyrecord_t *record) {
                 case KC_ENTER:
                     ucis_finish();
                     return false;
+                default:
+                    return false;
             }
         }
     }
diff --git a/quantum/unicode/ucis.c b/quantum/unicode/ucis.c
index 32be78520654..58cf927d7765 100644
--- a/quantum/unicode/ucis.c
+++ b/quantum/unicode/ucis.c
@@ -37,15 +37,19 @@ static char keycode_to_char(uint16_t keycode) {
 
 bool ucis_add(uint16_t keycode) {
     char c = keycode_to_char(keycode);
-    if (c) {
-        input[count++] = c;
-        return true;
+    if (count < UCIS_MAX_INPUT_LENGTH - 1) {
+        if (c) {
+            input[count++] = c;
+            input[count]   = 0;
+            return true;
+        }
     }
     return false;
 }
 
 bool ucis_remove_last(void) {
     if (count) {
+        input[count] = 0;
         count--;
         return true;
     }
@@ -72,10 +76,11 @@ void ucis_finish(void) {
         }
     }
 
+    for (uint8_t j = 0; j <= count; j++) {
+        tap_code(KC_BACKSPACE);
+    }
+
     if (found) {
-        for (uint8_t j = 0; j <= count; j++) {
-            tap_code(KC_BACKSPACE);
-        }
         register_ucis(i);
     }
 
@@ -83,6 +88,10 @@ void ucis_finish(void) {
 }
 
 void ucis_cancel(void) {
+    for (uint8_t i = 0; i <= count; i++) {
+        tap_code(KC_BACKSPACE);
+    }
+
     count  = 0;
     active = false;
 }