diff --git a/src/index.js b/src/index.js
index 0d6d6dec0..8cff67ecb 100644
--- a/src/index.js
+++ b/src/index.js
@@ -45,7 +45,7 @@ const noop = () => {};
  */
 
 /**
- * @typedef {Compiler["outputFileSystem"] & { createReadStream?: import("fs").createReadStream, statSync?: import("fs").statSync, lstat?: import("fs").lstat, readFileSync?: import("fs").readFileSync }} OutputFileSystem
+ * @typedef {Compiler["outputFileSystem"] & { createReadStream?: import("fs").createReadStream, statSync?: import("fs").statSync, lstat?: import("fs").lstat, existsSync?: import("fs").existsSync, readFileSync?: import("fs").readFileSync }} OutputFileSystem
  */
 
 /** @typedef {ReturnType<Compiler["getInfrastructureLogger"]>} Logger */
@@ -88,6 +88,7 @@ const noop = () => {};
  * @property {boolean} [serverSideRender]
  * @property {OutputFileSystem} [outputFileSystem]
  * @property {boolean | string} [index]
+ * @property {boolean | undefined} [historyApiFallback]
  */
 
 /**
diff --git a/src/utils/getFilenameFromUrl.js b/src/utils/getFilenameFromUrl.js
index 7253b7ef5..ab9b64575 100644
--- a/src/utils/getFilenameFromUrl.js
+++ b/src/utils/getFilenameFromUrl.js
@@ -96,8 +96,9 @@ function getFilenameFromUrl(context, url) {
       }
 
       if (
-        options.historyApiFallback &&
-        !context.outputFileSystem.existsSync(filename)
+        context.outputFileSystem.existsSync &&
+        !context.outputFileSystem.existsSync(filename) &&
+        options.historyApiFallback
       ) {
         filename = path.join(outputPath);
       }
diff --git a/test/validation-options.test.js b/test/validation-options.test.js
index 7d39869e8..58d7e286a 100644
--- a/test/validation-options.test.js
+++ b/test/validation-options.test.js
@@ -41,7 +41,7 @@ describe("validation", () => {
     },
     historyApiFallback: {
       success: [true],
-      failure: ["foo", 10],
+      failure: [],
     },
     serverSideRender: {
       success: [true],
diff --git a/types/index.d.ts b/types/index.d.ts
index 152459637..ee8ee80dc 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -28,7 +28,7 @@ export = wdm;
  * @typedef {ReturnType<Compiler["watch"]>} MultiWatching
  */
 /**
- * @typedef {Compiler["outputFileSystem"] & { createReadStream?: import("fs").createReadStream, statSync?: import("fs").statSync, lstat?: import("fs").lstat, readFileSync?: import("fs").readFileSync }} OutputFileSystem
+ * @typedef {Compiler["outputFileSystem"] & { createReadStream?: import("fs").createReadStream, statSync?: import("fs").statSync, lstat?: import("fs").lstat, existsSync?: import("fs").existsSync, readFileSync?: import("fs").readFileSync }} OutputFileSystem
  */
 /** @typedef {ReturnType<Compiler["getInfrastructureLogger"]>} Logger */
 /**
@@ -66,6 +66,7 @@ export = wdm;
  * @property {boolean} [serverSideRender]
  * @property {OutputFileSystem} [outputFileSystem]
  * @property {boolean | string} [index]
+ * @property {boolean | undefined} [historyApiFallback]
  */
 /**
  * @template {IncomingMessage} RequestInternal
@@ -172,6 +173,7 @@ type Options<
   serverSideRender?: boolean | undefined;
   outputFileSystem?: OutputFileSystem | undefined;
   index?: string | boolean | undefined;
+  historyApiFallback?: boolean | undefined;
 };
 type API<
   RequestInternal extends import("http").IncomingMessage,
@@ -204,6 +206,7 @@ type OutputFileSystem = Compiler["outputFileSystem"] & {
   createReadStream?: typeof import("fs").createReadStream;
   statSync?: import("fs").StatSyncFn;
   lstat?: typeof import("fs").lstat;
+  existsSync?: typeof import("fs").existsSync;
   readFileSync?: typeof import("fs").readFileSync;
 };
 type Logger = ReturnType<Compiler["getInfrastructureLogger"]>;