diff --git a/src/fixes/typescript.js b/src/fixes/typescript.js
index 5c2072d..a1022c8 100644
--- a/src/fixes/typescript.js
+++ b/src/fixes/typescript.js
@@ -11,14 +11,13 @@ export function fixReferences(contents, options = {}) {
   const removeAll = !options.types || options.types === 'all';
   const find = removeAll ? `/ <reference types=` : `/ <reference types="${options.types}`;
 
-  const fixed = root
+  root
     // @ts-expect-error
     .find(j.Comment)
     // @ts-expect-error
     .filter((path) => path.value.value.startsWith(find))
     // @ts-expect-error
-    .forEach((path) => j(path).remove())
-    .toSource();
+    .forEach((path) => j(path).remove());
 
-  return fixed;
+  return root.toSource();
 }
diff --git a/src/fixes/typescript.test.ts b/src/fixes/typescript.test.ts
index a2318f7..da6fa14 100644
--- a/src/fixes/typescript.test.ts
+++ b/src/fixes/typescript.test.ts
@@ -76,4 +76,66 @@ describe('fixReferences', () => {
 
     expect(result).toBe(`export const two = 2;`);
   });
+
+  describe('https://github.com/machty/ember-concurrency/issues/564', () => {
+    test('declarations/helpers/cancel-all.d.ts', () => {
+      let code = stripIndent`
+        /// <reference types="ember-source/types/preview/@ember/component/-private/signature-utils" />
+        /// <reference types="ember-source/types/preview/@ember/component/helper" />
+        import type { Task } from '../index';
+        type CancelAllParams = [task: Task<any, any[]>];
+        export declare function cancelHelper(args: CancelAllParams): (...innerArgs: any[]) => any;
+        declare const _default: import("@ember/component/helper").FunctionBasedHelper<{
+            Args: {
+                Positional: CancelAllParams;
+                Named: import("@ember/component/helper").EmptyObject;
+            };
+            Return: (...innerArgs: any[]) => any;
+        }>;
+        export default _default;
+      `;
+
+      let result = fixReferences(code);
+
+      expect(result).toMatchInlineSnapshot(`
+        "import type { Task } from '../index';
+        type CancelAllParams = [task: Task<any, any[]>];
+        export declare function cancelHelper(args: CancelAllParams): (...innerArgs: any[]) => any;
+        declare const _default: import("@ember/component/helper").FunctionBasedHelper<{
+            Args: {
+                Positional: CancelAllParams;
+                Named: import("@ember/component/helper").EmptyObject;
+            };
+            Return: (...innerArgs: any[]) => any;
+        }>;
+        export default _default;"
+      `);
+    });
+
+    test('declarations/-private/ember-environment.d.ts', () => {
+      let code = stripIndent`
+        export declare class EmberEnvironment extends Environment {
+            assert(...args: any[]): void;
+            reportUncaughtRejection(error: any): void;
+            defer(): any;
+            globalDebuggingEnabled(): any;
+        }
+        export declare const EMBER_ENVIRONMENT: EmberEnvironment;
+        import { Environment } from './external/environment';
+      `;
+
+      let result = fixReferences(code);
+
+      expect(result).toMatchInlineSnapshot(`
+        "export declare class EmberEnvironment extends Environment {
+            assert(...args: any[]): void;
+            reportUncaughtRejection(error: any): void;
+            defer(): any;
+            globalDebuggingEnabled(): any;
+        }
+        export declare const EMBER_ENVIRONMENT: EmberEnvironment;
+        import { Environment } from './external/environment';"
+      `);
+    });
+  });
 });
diff --git a/src/index.test.ts b/src/index.test.ts
index 334f21f..0906645 100644
--- a/src/index.test.ts
+++ b/src/index.test.ts
@@ -39,7 +39,10 @@ describe('fixBadDeclarationOutput', () => {
       /// <reference types="@glint/whatever/module">
       /// <reference types="node_modules/@glint/whatever2/module">
       /// <reference types="xyz">
+
       export declare const two: number;
+      export declare const three: string;
+      export declare const four: 'literal';
     `
     );
 
@@ -49,6 +52,10 @@ describe('fixBadDeclarationOutput', () => {
 
     let aContents = await read(a);
 
-    expect(aContents).toBe(`export declare const two: number;`);
+    expect(aContents).toMatchInlineSnapshot(`
+      "export declare const two: number;
+      export declare const three: string;
+      export declare const four: 'literal';"
+    `);
   });
 });