diff --git a/src/components/arrowLigaturesExtension.ts b/src/components/arrowLigaturesExtension.ts
index 83169ef4..f7aec33f 100644
--- a/src/components/arrowLigaturesExtension.ts
+++ b/src/components/arrowLigaturesExtension.ts
@@ -3,7 +3,7 @@ import { resolveArrowLigatureInput } from '../utils/arrowLigatures'
 
 const PREFIX_CONTEXT_LENGTH = 2
 
-function isInsertedCharacter(event: InputEvent) {
+function isInsertedCharacter(event: InputEvent): event is InputEvent & { data: string } {
   return event.inputType === 'insertText' && typeof event.data === 'string'
 }
 
diff --git a/src/hooks/useCodeMirror.ts b/src/hooks/useCodeMirror.ts
index fdc78881..83ec58b0 100644
--- a/src/hooks/useCodeMirror.ts
+++ b/src/hooks/useCodeMirror.ts
@@ -78,7 +78,7 @@ function buildSaveKeymap(callbacks: { current: CodeMirrorCallbacks }) {
 function buildArrowLigaturesExtension() {
   let literalAsciiCursor: number | null = null
 
-  return EditorView.inputHandler.of((view, from, to, text) => {
+  return EditorView.inputHandler.of((view, from, _to, text) => {
     const beforeText = view.state.doc.sliceString(Math.max(0, from - 2), from)
     const resolution = resolveArrowLigatureInput({
       beforeText,