diff --git a/stubs/color-diff-napi.ts b/stubs/color-diff-napi.ts
index b0b6fd1..ad1fbfd 100644
--- a/stubs/color-diff-napi.ts
+++ b/stubs/color-diff-napi.ts
@@ -1,19 +1,45 @@
 export type SyntaxTheme = {
-  name: string;
+  theme: string;
+  source: string | null;
 };
 
 export class ColorDiff {
-  format(input: string): string {
-    return input;
+  private hunk: { oldStart: number; oldLines: number; newStart: number; newLines: number; lines: string[] };
+  private filePath: string;
+  private firstLine: string | null;
+  private prefixContent: string | null;
+
+  constructor(
+    hunk: { oldStart: number; oldLines: number; newStart: number; newLines: number; lines: string[] },
+    firstLine: string | null,
+    filePath: string,
+    prefixContent?: string | null,
+  ) {
+    this.hunk = hunk;
+    this.filePath = filePath;
+    this.firstLine = firstLine;
+    this.prefixContent = prefixContent ?? null;
+  }
+
+  render(themeName: string, width: number, dim: boolean): string[] | null {
+    return null;
   }
 }
 
 export class ColorFile {
-  format(input: string): string {
-    return input;
+  private code: string;
+  private filePath: string;
+
+  constructor(code: string, filePath: string) {
+    this.code = code;
+    this.filePath = filePath;
+  }
+
+  render(themeName: string, width: number, dim: boolean): string[] | null {
+    return null;
   }
 }
 
 export function getSyntaxTheme(themeName: string): SyntaxTheme {
-  return { name: themeName };
+  return { theme: themeName, source: null };
 }