diff --git a/compiler/packages/snap/src/compiler.ts b/compiler/packages/snap/src/compiler.ts
index 3210e235c761c..5c9d841dcffe6 100644
--- a/compiler/packages/snap/src/compiler.ts
+++ b/compiler/packages/snap/src/compiler.ts
@@ -270,8 +270,11 @@ function getEvaluatorPresets(
   );
   return presets;
 }
-function format(inputCode: string, language: "typescript" | "flow"): string {
-  return prettier.format(inputCode, {
+async function format(
+  inputCode: string,
+  language: "typescript" | "flow",
+): Promise<string> {
+  return await prettier.format(inputCode, {
     semi: true,
     parser: language === "typescript" ? "babel-ts" : "flow",
   });
@@ -287,13 +290,15 @@ export type TransformResult = {
   } | null;
 };
 
-export function transformFixtureInput(
+export async function transformFixtureInput(
   input: string,
   fixturePath: string,
   parseConfigPragmaFn: typeof ParseConfigPragma,
   plugin: BabelCore.PluginObj,
   includeEvaluator: boolean,
-): { kind: "ok"; value: TransformResult } | { kind: "err"; msg: string } {
+): Promise<
+  { kind: "ok"; value: TransformResult } | { kind: "err"; msg: string }
+> {
   // Extract the first line to quickly check for custom test directives
   const firstLine = input.substring(0, input.indexOf("\n"));
 
@@ -400,7 +405,7 @@ export function transformFixtureInput(
   return {
     kind: "ok",
     value: {
-      forgetOutput: format(forgetOutput, language),
+      forgetOutput: await format(forgetOutput, language),
       evaluatorCode,
     },
   };
diff --git a/compiler/packages/snap/src/runner-worker.ts b/compiler/packages/snap/src/runner-worker.ts
index ac7ed5af7c4da..e42bc6a236e2a 100644
--- a/compiler/packages/snap/src/runner-worker.ts
+++ b/compiler/packages/snap/src/runner-worker.ts
@@ -33,16 +33,16 @@ export function clearRequireCache() {
   });
 }
 
-function compile(
+async function compile(
   input: string,
   fixturePath: string,
   compilerVersion: number,
   shouldLog: boolean,
   includeEvaluator: boolean,
-): {
+): Promise<{
   error: string | null;
   compileResult: TransformResult | null;
-} {
+}> {
   const seenConsoleErrors: Array<string> = [];
   console.error = (...messages: Array<string>) => {
     seenConsoleErrors.push(...messages);
@@ -68,7 +68,7 @@ function compile(
     // only try logging if we filtered out all but one fixture,
     // since console log order is non-deterministic
     toggleLogging(shouldLog);
-    const result = transformFixtureInput(
+    const result = await transformFixtureInput(
       input,
       fixturePath,
       parseConfigPragma,
@@ -147,7 +147,7 @@ export async function transformFixture(
       unexpectedError: null,
     };
   }
-  const { compileResult, error } = compile(
+  const { compileResult, error } = await compile(
     input,
     fixture.fixturePath,
     compilerVersion,