diff --git a/lib/index.d.ts b/lib/index.d.ts
index ae66ffb..7f4a2d0 100644
--- a/lib/index.d.ts
+++ b/lib/index.d.ts
@@ -7,6 +7,8 @@
  *   original.
  * @prop {boolean} [noOriginal] Do not run tests on the original code, only
  *   on the generated code.
+ * @prop {boolean} [inputSourceMap] Read sourceMap information from the input
+ *   file.  Use it to filter the generated sourceMap information.
  */
 /**
  * Test the basic functionality of a Peggy grammar, to make coverage easier.
@@ -113,4 +115,9 @@ export type TestPeggyOptions = {
      * on the generated code.
      */
     noOriginal?: boolean | undefined;
+    /**
+     * Read sourceMap information from the input
+     * file.  Use it to filter the generated sourceMap information.
+     */
+    inputSourceMap?: boolean | undefined;
 };
diff --git a/lib/index.js b/lib/index.js
index 60bea6b..240289b 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,3 +1,4 @@
+import { SourceMapConsumer, SourceNode } from "source-map";
 import {
   deepEqual,
   equal,
@@ -5,12 +6,14 @@ import {
   ok,
   throws,
 } from "node:assert/strict";
-import { SourceNode } from "source-map";
 import { fileURLToPath } from "node:url";
 import fs from "node:fs/promises";
 import path from "node:path";
 
 const INVALID = "\uffff";
+const START = "//#"; // c8: THIS file is not mapped.
+const sourceMapRE = new RegExp(`^${START}\\s*sourceMappingURL\\s*=\\s*([^\r\n]+)`, "m");
+const startRuleRE = /^\s*peg\$result = peg\$startRuleFunction\(\);/;
 let counter = 0;
 
 /**
@@ -258,6 +261,8 @@ function checkParserStarts(grammar, starts, modified, counts) {
  *   original.
  * @prop {boolean} [noOriginal] Do not run tests on the original code, only
  *   on the generated code.
+ * @prop {boolean} [inputSourceMap] Read sourceMap information from the input
+ *   file.  Use it to filter the generated sourceMap information.
  */
 
 /**
@@ -333,13 +338,47 @@ export async function testPeggy(grammarUrl, starts, opts) {
     ok(grammarJs);
     equal(typeof grammarJs, "string");
 
+    /** @type {SourceMapConsumer|null} */
+    let ism = null;
+    if (opts?.inputSourceMap) {
+      const m = grammarJs.match(sourceMapRE);
+      if (m) {
+        const map = m[1].startsWith("data:")
+          ? await (await fetch(m[1])).json()
+          : JSON.parse(
+              await fs.readFile(
+                path.resolve(process.cwd(), path.dirname(grammarPath), m[1]),
+                "utf8"
+              )
+            );
+        ism = await new SourceMapConsumer(map);
+      }
+    }
+
     // Approach: generate a new file next to the existing grammar file, with
     // test code injected just before the parser runs.  Source map information
     // embedded in the new file will make coverage show up on the original file.
     const src = new SourceNode();
     let lineNum = 1;
     for (const line of grammarJs.split(/(?<=\n)/)) {
-      if (/^\s*peg\$result = peg\$startRuleFunction\(\);/.test(line)) {
+      let sn = null;
+      if (ism) {
+        const pos = ism.originalPositionFor({
+          line: lineNum,
+          column: 0,
+        });
+        if (pos) {
+          sn = new SourceNode(pos.line, pos.column, pos.source, line);
+        }
+      }
+      if (!sn) {
+        sn = new SourceNode(lineNum, 0, grammarPath, line);
+      }
+      lineNum++;
+
+      if (sourceMapRE.test(line)) {
+        // No-op, never output sourcemapurl line.
+      } else if (startRuleRE.test(line)) {
         src.add(`\
   //#region Inserted by @peggyjs/coverage
   let replacements = Object.create(null);
@@ -440,7 +479,7 @@ export async function testPeggy(grammarUrl, starts, opts) {
   //#endregion
 
 `);
-        src.add(new SourceNode(lineNum++, 0, grammarPath, line));
+        src.add(sn);
         src.add(`
   //#region Inserted by @peggyjs/coverage
   for (const [name, orig] of Object.entries(replacements)) {
@@ -450,7 +489,7 @@ export async function testPeggy(grammarUrl, starts, opts) {
   //#endregion
 `);
       } else {
-        src.add(new SourceNode(lineNum++, 0, grammarPath, line));
+        src.add(sn);
       }
     }
 
@@ -460,17 +499,15 @@ export async function testPeggy(grammarUrl, starts, opts) {
     let sm = starts.every(s => !s.options?.peg$debugger);
     if (opts && Object.prototype.hasOwnProperty.call(opts, "noMap")) {
       sm = !opts.noMap;
-    } else {
-      if (!sm) {
-        console.error("WARNING: sourcemap disabled due to peg$debugger");
-      }
+    } else if (!sm) {
+      console.error("WARNING: sourcemap disabled due to peg$debugger");
     }
-    const start = "//#"; // c8: THIS file is not mapped.
     if (sm) {
       code += `
-${start} sourceMappingURL=data:application/json;charset=utf-8;base64,${map}
+${START} sourceMappingURL=data:application/json;charset=utf-8;base64,${map}
 `;
     }
+    ism?.destroy();
     await fs.writeFile(modifiedPath, code);
     try {
       const agrammar = /** @type {Parser} */ (
diff --git a/package.json b/package.json
index a334cba..7c0020e 100644
--- a/package.json
+++ b/package.json
@@ -37,10 +37,10 @@
   },
   "devDependencies": {
     "@peggyjs/eslint-config": "6.0.0",
-    "@types/node": "22.15.3",
+    "@types/node": "22.15.14",
     "c8": "10.1.3",
     "eslint": "9.26.0",
-    "typedoc": "0.28.3",
+    "typedoc": "0.28.4",
     "typescript": "5.8.3"
   },
   "packageManager": "pnpm@10.10.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index d870369..bf12b7e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -19,8 +19,8 @@ importers:
         specifier: 6.0.0
         version: 6.0.0(eslint@9.26.0)(typescript@5.8.3)
       '@types/node':
-        specifier: 22.15.3
-        version: 22.15.3
+        specifier: 22.15.14
+        version: 22.15.14
       c8:
         specifier: 10.1.3
         version: 10.1.3
@@ -28,8 +28,8 @@ importers:
         specifier: 9.26.0
         version: 9.26.0
       typedoc:
-        specifier: 0.28.3
-        version: 0.28.3(typescript@5.8.3)
+        specifier: 0.28.4
+        version: 0.28.4(typescript@5.8.3)
       typescript:
         specifier: 5.8.3
         version: 5.8.3
@@ -167,17 +167,17 @@ packages:
     resolution: {integrity: sha512-+1VkjdD0QBLPodGrJUeqarH8VAIvQODIbwh9XpP5Syisf7YoQgsJKPNFoqqLQlu+VQ/tVSshMR6loPMn8U+dPg==}
     engines: {node: '>=14'}
 
-  '@shikijs/engine-oniguruma@3.3.0':
-    resolution: {integrity: sha512-l0vIw+GxeNU7uGnsu6B+Crpeqf+WTQ2Va71cHb5ZYWEVEPdfYwY5kXwYqRJwHrxz9WH+pjSpXQz+TJgAsrkA5A==}
+  '@shikijs/engine-oniguruma@3.4.0':
+    resolution: {integrity: sha512-zwcWlZ4OQuJ/+1t32ClTtyTU1AiDkK1lhtviRWoq/hFqPjCNyLj22bIg9rB7BfoZKOEOfrsGz7No33BPCf+WlQ==}
 
-  '@shikijs/langs@3.3.0':
-    resolution: {integrity: sha512-zt6Kf/7XpBQKSI9eqku+arLkAcDQ3NHJO6zFjiChI8w0Oz6Jjjay7pToottjQGjSDCFk++R85643WbyINcuL+g==}
+  '@shikijs/langs@3.4.0':
+    resolution: {integrity: sha512-bQkR+8LllaM2duU9BBRQU0GqFTx7TuF5kKlw/7uiGKoK140n1xlLAwCgXwSxAjJ7Htk9tXTFwnnsJTCU5nDPXQ==}
 
-  '@shikijs/themes@3.3.0':
-    resolution: {integrity: sha512-tXeCvLXBnqq34B0YZUEaAD1lD4lmN6TOHAhnHacj4Owh7Ptb/rf5XCDeROZt2rEOk5yuka3OOW2zLqClV7/SOg==}
+  '@shikijs/themes@3.4.0':
+    resolution: {integrity: sha512-YPP4PKNFcFGLxItpbU0ZW1Osyuk8AyZ24YEFaq04CFsuCbcqydMvMUTi40V2dkc0qs1U2uZFrnU6s5zI6IH+uA==}
 
-  '@shikijs/types@3.3.0':
-    resolution: {integrity: sha512-KPCGnHG6k06QG/2pnYGbFtFvpVJmC3uIpXrAiPrawETifujPBv0Se2oUxm5qYgjCvGJS9InKvjytOdN+bGuX+Q==}
+  '@shikijs/types@3.4.0':
+    resolution: {integrity: sha512-EUT/0lGiE//7j5N/yTMNMT3eCWNcHJLrRKxT0NDXWIfdfSmFJKfPX7nMmRBrQnWboAzIsUziCThrYMMhjbMS1A==}
 
   '@shikijs/vscode-textmate@10.0.2':
     resolution: {integrity: sha512-83yeghZ2xxin3Nj8z1NMd/NCuca+gsYXswywDy5bHvwlWL8tpTQmzGeUuHd9FC3E/SBEMvzJRwWEOz5gGes9Qg==}
@@ -209,35 +209,35 @@ packages:
   '@types/ms@2.1.0':
     resolution: {integrity: sha512-GsCCIZDE/p3i96vtEqx+7dBUGXrc7zeSK3wwPHIaRThS+9OhWIXRqzs4d6k1SVU8g91DrNRWxWUGhp5KXQb2VA==}
 
-  '@types/node@22.15.3':
-    resolution: {integrity: sha512-lX7HFZeHf4QG/J7tBZqrCAXwz9J5RD56Y6MpP0eJkka8p+K0RY/yBTW7CYFJ4VGCclxqOLKmiGP5juQc6MKgcw==}
+  '@types/node@22.15.14':
+    resolution: {integrity: sha512-BL1eyu/XWsFGTtDWOYULQEs4KR0qdtYfCxYAUYRoB7JP7h9ETYLgQTww6kH8Sj2C0pFGgrpM0XKv6/kbIzYJ1g==}
 
   '@types/unist@3.0.3':
     resolution: {integrity: sha512-ko/gIFJRv177XgZsZcBwnqJN5x/Gien8qNOn0D5bQU/zAzVf9Zt3BlcUiLqhV9y4ARk0GbT3tnUiPNgnTXzc/Q==}
 
-  '@typescript-eslint/scope-manager@8.31.1':
-    resolution: {integrity: sha512-BMNLOElPxrtNQMIsFHE+3P0Yf1z0dJqV9zLdDxN/xLlWMlXK/ApEsVEKzpizg9oal8bAT5Sc7+ocal7AC1HCVw==}
+  '@typescript-eslint/scope-manager@8.32.0':
+    resolution: {integrity: sha512-jc/4IxGNedXkmG4mx4nJTILb6TMjL66D41vyeaPWvDUmeYQzF3lKtN15WsAeTr65ce4mPxwopPSo1yUUAWw0hQ==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
 
-  '@typescript-eslint/types@8.31.1':
-    resolution: {integrity: sha512-SfepaEFUDQYRoA70DD9GtytljBePSj17qPxFHA/h3eg6lPTqGJ5mWOtbXCk1YrVU1cTJRd14nhaXWFu0l2troQ==}
+  '@typescript-eslint/types@8.32.0':
+    resolution: {integrity: sha512-O5Id6tGadAZEMThM6L9HmVf5hQUXNSxLVKeGJYWNhhVseps/0LddMkp7//VDkzwJ69lPL0UmZdcZwggj9akJaA==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
 
-  '@typescript-eslint/typescript-estree@8.31.1':
-    resolution: {integrity: sha512-kaA0ueLe2v7KunYOyWYtlf/QhhZb7+qh4Yw6Ni5kgukMIG+iP773tjgBiLWIXYumWCwEq3nLW+TUywEp8uEeag==}
+  '@typescript-eslint/typescript-estree@8.32.0':
+    resolution: {integrity: sha512-pU9VD7anSCOIoBFnhTGfOzlVFQIA1XXiQpH/CezqOBaDppRwTglJzCC6fUQGpfwey4T183NKhF1/mfatYmjRqQ==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
     peerDependencies:
       typescript: '>=4.8.4 <5.9.0'
 
-  '@typescript-eslint/utils@8.31.1':
-    resolution: {integrity: sha512-2DSI4SNfF5T4oRveQ4nUrSjUqjMND0nLq9rEkz0gfGr3tg0S5KB6DhwR+WZPCjzkZl3cH+4x2ce3EsL50FubjQ==}
+  '@typescript-eslint/utils@8.32.0':
+    resolution: {integrity: sha512-8S9hXau6nQ/sYVtC3D6ISIDoJzS1NsCK+gluVhLN2YkBPX+/1wkwyUiDKnxRh15579WoOIyVWnoyIf3yGI9REw==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
     peerDependencies:
       eslint: ^8.57.0 || ^9.0.0
       typescript: '>=4.8.4 <5.9.0'
 
-  '@typescript-eslint/visitor-keys@8.31.1':
-    resolution: {integrity: sha512-I+/rgqOVBn6f0o7NDTmAPWWC6NuqhV174lfYvAm9fUaWeiefLdux9/YI3/nLugEn9L8fcSi0XmpKi/r5u0nmpw==}
+  '@typescript-eslint/visitor-keys@8.32.0':
+    resolution: {integrity: sha512-1rYQTCLFFzOI5Nl0c8LUpJT8HxpwVRn9E4CkMsYfuN6ctmQqExjSTzzSk0Tz2apmXy7WU6/6fyaZVVA/thPN+w==}
     engines: {node: ^18.18.0 || ^20.9.0 || >=21.1.0}
 
   accepts@2.0.0:
@@ -1149,8 +1149,8 @@ packages:
     resolution: {integrity: sha512-OZs6gsjF4vMp32qrCbiVSkrFmXtG/AZhY3t0iAMrMBiAZyV9oALtXO8hsrHbMXF9x6L3grlFuwW2oAz7cav+Gw==}
     engines: {node: '>= 0.6'}
 
-  typedoc@0.28.3:
-    resolution: {integrity: sha512-5svOCTfXvVSh6zbZKSQluZhR8yN2tKpTeHZxlmWpE6N5vc3R8k/jhg9nnD6n5tN9/ObuQTojkONrOxFdUFUG9w==}
+  typedoc@0.28.4:
+    resolution: {integrity: sha512-xKvKpIywE1rnqqLgjkoq0F3wOqYaKO9nV6YkkSat6IxOWacUCc/7Es0hR3OPmkIqkPoEn7U3x+sYdG72rstZQA==}
     engines: {node: '>= 18', pnpm: '>= 10'}
     hasBin: true
     peerDependencies:
@@ -1240,8 +1240,8 @@ packages:
     peerDependencies:
       zod: ^3.24.1
 
-  zod@3.24.3:
-    resolution: {integrity: sha512-HhY1oqzWCQWuUqvBFnsyrtZRhyPeR7SUGv+C4+MsisMuVfSPx8HpwWqH8tRahSlt6M3PiFAcoeFhZAqIXTxoSg==}
+  zod@3.24.4:
+    resolution: {integrity: sha512-OdqJE9UDRPwWsrHjLN2F8bPxvwJBK22EHLWtanu0LSYr5YqzsaaW3RMgmjwr8Rypg5k+meEJdSPXJZXE/yqOMg==}
 
   zwitch@2.0.4:
     resolution: {integrity: sha512-bXE4cR/kVZhKZX/RjPEflHaKVhUVl85noU3v6b8apfQEc1x4A+zBxjZ4lN8LqGd6WZ3dl98pY4o717VFmoPp+A==}
@@ -1323,10 +1323,10 @@ snapshots:
 
   '@gerrit0/mini-shiki@3.3.0':
     dependencies:
-      '@shikijs/engine-oniguruma': 3.3.0
-      '@shikijs/langs': 3.3.0
-      '@shikijs/themes': 3.3.0
-      '@shikijs/types': 3.3.0
+      '@shikijs/engine-oniguruma': 3.4.0
+      '@shikijs/langs': 3.4.0
+      '@shikijs/themes': 3.4.0
+      '@shikijs/types': 3.4.0
       '@shikijs/vscode-textmate': 10.0.2
 
   '@humanfs/core@0.19.1': {}
@@ -1374,8 +1374,8 @@ snapshots:
       express-rate-limit: 7.5.0(express@5.1.0)
       pkce-challenge: 5.0.0
       raw-body: 3.0.0
-      zod: 3.24.3
-      zod-to-json-schema: 3.24.5(zod@3.24.3)
+      zod: 3.24.4
+      zod-to-json-schema: 3.24.5(zod@3.24.4)
     transitivePeerDependencies:
       - supports-color
 
@@ -1409,20 +1409,20 @@ snapshots:
   '@pkgjs/parseargs@0.11.0':
     optional: true
 
-  '@shikijs/engine-oniguruma@3.3.0':
+  '@shikijs/engine-oniguruma@3.4.0':
     dependencies:
-      '@shikijs/types': 3.3.0
+      '@shikijs/types': 3.4.0
       '@shikijs/vscode-textmate': 10.0.2
 
-  '@shikijs/langs@3.3.0':
+  '@shikijs/langs@3.4.0':
     dependencies:
-      '@shikijs/types': 3.3.0
+      '@shikijs/types': 3.4.0
 
-  '@shikijs/themes@3.3.0':
+  '@shikijs/themes@3.4.0':
     dependencies:
-      '@shikijs/types': 3.3.0
+      '@shikijs/types': 3.4.0
 
-  '@shikijs/types@3.3.0':
+  '@shikijs/types@3.4.0':
     dependencies:
       '@shikijs/vscode-textmate': 10.0.2
       '@types/hast': 3.0.4
@@ -1431,7 +1431,7 @@ snapshots:
 
   '@stylistic/eslint-plugin@4.2.0(eslint@9.26.0)(typescript@5.8.3)':
     dependencies:
-      '@typescript-eslint/utils': 8.31.1(eslint@9.26.0)(typescript@5.8.3)
+      '@typescript-eslint/utils': 8.32.0(eslint@9.26.0)(typescript@5.8.3)
       eslint: 9.26.0
       eslint-visitor-keys: 4.2.0
       espree: 10.3.0
@@ -1461,23 +1461,23 @@ snapshots:
 
   '@types/ms@2.1.0': {}
 
-  '@types/node@22.15.3':
+  '@types/node@22.15.14':
     dependencies:
       undici-types: 6.21.0
 
   '@types/unist@3.0.3': {}
 
-  '@typescript-eslint/scope-manager@8.31.1':
+  '@typescript-eslint/scope-manager@8.32.0':
     dependencies:
-      '@typescript-eslint/types': 8.31.1
-      '@typescript-eslint/visitor-keys': 8.31.1
+      '@typescript-eslint/types': 8.32.0
+      '@typescript-eslint/visitor-keys': 8.32.0
 
-  '@typescript-eslint/types@8.31.1': {}
+  '@typescript-eslint/types@8.32.0': {}
 
-  '@typescript-eslint/typescript-estree@8.31.1(typescript@5.8.3)':
+  '@typescript-eslint/typescript-estree@8.32.0(typescript@5.8.3)':
     dependencies:
-      '@typescript-eslint/types': 8.31.1
-      '@typescript-eslint/visitor-keys': 8.31.1
+      '@typescript-eslint/types': 8.32.0
+      '@typescript-eslint/visitor-keys': 8.32.0
       debug: 4.4.0
       fast-glob: 3.3.3
       is-glob: 4.0.3
@@ -1488,20 +1488,20 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
-  '@typescript-eslint/utils@8.31.1(eslint@9.26.0)(typescript@5.8.3)':
+  '@typescript-eslint/utils@8.32.0(eslint@9.26.0)(typescript@5.8.3)':
     dependencies:
       '@eslint-community/eslint-utils': 4.7.0(eslint@9.26.0)
-      '@typescript-eslint/scope-manager': 8.31.1
-      '@typescript-eslint/types': 8.31.1
-      '@typescript-eslint/typescript-estree': 8.31.1(typescript@5.8.3)
+      '@typescript-eslint/scope-manager': 8.32.0
+      '@typescript-eslint/types': 8.32.0
+      '@typescript-eslint/typescript-estree': 8.32.0(typescript@5.8.3)
       eslint: 9.26.0
       typescript: 5.8.3
     transitivePeerDependencies:
       - supports-color
 
-  '@typescript-eslint/visitor-keys@8.31.1':
+  '@typescript-eslint/visitor-keys@8.32.0':
     dependencies:
-      '@typescript-eslint/types': 8.31.1
+      '@typescript-eslint/types': 8.32.0
       eslint-visitor-keys: 4.2.0
 
   accepts@2.0.0:
@@ -1738,7 +1738,7 @@ snapshots:
       minimatch: 3.1.2
       natural-compare: 1.4.0
       optionator: 0.9.4
-      zod: 3.24.3
+      zod: 3.24.4
     transitivePeerDependencies:
       - supports-color
 
@@ -2612,7 +2612,7 @@ snapshots:
       media-typer: 1.1.0
       mime-types: 3.0.1
 
-  typedoc@0.28.3(typescript@5.8.3):
+  typedoc@0.28.4(typescript@5.8.3):
     dependencies:
       '@gerrit0/mini-shiki': 3.3.0
       lunr: 2.3.9
@@ -2698,10 +2698,10 @@ snapshots:
 
   yocto-queue@0.1.0: {}
 
-  zod-to-json-schema@3.24.5(zod@3.24.3):
+  zod-to-json-schema@3.24.5(zod@3.24.4):
     dependencies:
-      zod: 3.24.3
+      zod: 3.24.4
 
-  zod@3.24.3: {}
+  zod@3.24.4: {}
 
   zwitch@2.0.4: {}
diff --git a/test/index.test.js b/test/index.test.js
index 35418b0..e7c5ef1 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -1,8 +1,17 @@
 import { deepEqual, equal, rejects } from "node:assert";
+import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
+import { SourceNode } from "source-map";
+import { join } from "node:path";
 import test from "node:test";
 import { testPeggy } from "../lib/index.js";
+import { tmpdir } from "node:os";
 
 const MIN = new URL("minimal.js", import.meta.url);
+const tmp = await mkdtemp(join(tmpdir(), "peggyjs-coverage-"));
+
+test.after(async() => {
+  await rm(tmp, { recursive: true });
+});
 
 function cleanCounts(counts) {
   equal(typeof counts.grammarPath, "string");
@@ -207,3 +216,55 @@ test("peg$debugger", async() => {
   console.error = old;
   deepEqual(stderr, [["WARNING: sourcemap disabled due to peg$debugger"]]);
 });
+
+test("inputSourceMap", async() => {
+  // MIN doesn't have sourcemap
+  await testPeggy(MIN, [
+    {
+      validInput: "foo",
+    },
+  ], {
+    inputSourceMap: true,
+  });
+
+  const tmpMin = join(tmp, "minimal.js");
+  const src = new SourceNode();
+  const tmpTxt = await readFile(MIN, "utf8");
+  let lineNum = 1;
+  for (const line of tmpTxt.split(/(?<=\n)/)) {
+    const sn = new SourceNode(lineNum++, 0, MIN, line);
+    src.add(sn);
+  }
+  const withMap = src.toStringWithSourceMap();
+  const map = Buffer.from(withMap.map.toString()).toString("base64");
+  const { code } = withMap;
+  const START = "//#";
+  const codeWithDataMap = code + `
+${START} sourceMappingURL=data:application/json;charset=utf-8;base64,${map}
+`;
+  await writeFile(tmpMin, codeWithDataMap);
+
+  // With data: URL
+  await testPeggy(tmpMin, [
+    {
+      validInput: "foo",
+    },
+  ], {
+    inputSourceMap: true,
+  });
+
+  // With file reference
+  const codeWithFileMap = code + `
+${START} sourceMappingURL=minimal.js.map
+`;
+  await writeFile(tmpMin, codeWithFileMap);
+  const tmpMinMap = join(tmp, "minimal.js.map");
+  await writeFile(tmpMinMap, withMap.map.toString());
+  await testPeggy(tmpMin, [
+    {
+      validInput: "foo",
+    },
+  ], {
+    inputSourceMap: true,
+  });
+});