diff --git a/domino-ui/src/main/java/org/dominokit/domino/ui/forms/NumberBox.java b/domino-ui/src/main/java/org/dominokit/domino/ui/forms/NumberBox.java
index 129d79c2..d067c427 100644
--- a/domino-ui/src/main/java/org/dominokit/domino/ui/forms/NumberBox.java
+++ b/domino-ui/src/main/java/org/dominokit/domino/ui/forms/NumberBox.java
@@ -116,7 +116,9 @@ protected String createKeyMatch() {
 
   protected void onKeyDown(Event event) {
     KeyboardEvent keyboardEvent = Js.uncheckedCast(event);
-    if (!keyboardEvent.key.matches(createKeyMatch())) event.preventDefault();
+    if (keyboardEvent.key.length() == 1 && !keyboardEvent.key.matches(createKeyMatch())) {
+      event.preventDefault();
+    }
   }
 
   protected void onPaste(Event event) {