diff --git a/src/CardinalUI.cpp b/src/CardinalUI.cpp
index 7e084b4..43e6919 100644
--- a/src/CardinalUI.cpp
+++ b/src/CardinalUI.cpp
@@ -236,7 +236,7 @@ protected:
 
     bool onCharacterInput(const CharacterInputEvent& ev) override
     {
-        if (ev.character == 0)
+        if (ev.character <= ' ' || ev.character >= kKeyDelete)
             return false;
 
         const ScopedContext sc(this);