diff --git a/src/common/Input.ts b/src/common/Input.ts
index 03d02a5768e68..1e2794b8a1c46 100644
--- a/src/common/Input.ts
+++ b/src/common/Input.ts
@@ -209,7 +209,7 @@ export class Keyboard {
   }
 
   private charIsKey(char: string): char is KeyInput {
-    return !!keyDefinitions[char];
+    return !!keyDefinitions[char as KeyInput];
   }
 
   /**
@@ -235,7 +235,7 @@ export class Keyboard {
    * Defaults to 0.
    */
   async type(text: string, options: { delay?: number } = {}): Promise<void> {
-    const delay = options.delay || null;
+    const delay = options.delay || undefined;
     for (const char of text) {
       if (this.charIsKey(char)) {
         await this.press(char, { delay });