diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 00000000..bf67d3d6
Binary files /dev/null and b/.DS_Store differ
diff --git a/README.md b/README.md
index 1d2741df..72402e35 100644
--- a/README.md
+++ b/README.md
@@ -240,6 +240,10 @@ following attributes:
 
 - `file`: Optional. The generated filename this source map is associated with.
 
+- `x_google_ignoreList`: Optional. An additional extension field which is an array
+  of indices refering to urls in the sources array. This is used to identify third-party
+  sources, that the developer might want to avoid when debugging. [Read more](https://developer.chrome.com/articles/x-google-ignore-list/)
+
 The promise of the constructed souce map consumer is returned.
 
 When the `SourceMapConsumer` will no longer be used anymore, you must call its
diff --git a/lib/source-map-consumer.js b/lib/source-map-consumer.js
index b2db4d55..be1289d9 100644
--- a/lib/source-map-consumer.js
+++ b/lib/source-map-consumer.js
@@ -187,6 +187,11 @@ class BasicSourceMapConsumer extends SourceMapConsumer {
       const sourcesContent = util.getArg(sourceMap, "sourcesContent", null);
       const mappings = util.getArg(sourceMap, "mappings");
       const file = util.getArg(sourceMap, "file", null);
+      const x_google_ignoreList = util.getArg(
+        sourceMap,
+        "x_google_ignoreList",
+        null
+      );
 
       // Once again, Sass deviates from the spec and supplies the version as a
       // string rather than a number, so we use loose equality checking here.
@@ -215,6 +220,7 @@ class BasicSourceMapConsumer extends SourceMapConsumer {
       that._mappings = mappings;
       that._sourceMapURL = aSourceMapURL;
       that.file = file;
+      that.x_google_ignoreList = x_google_ignoreList;
 
       that._computedColumnSpans = false;
       that._mappingsPtr = 0;
diff --git a/test/test-source-map-consumer.js b/test/test-source-map-consumer.js
index 23b2a34f..1bc09b85 100644
--- a/test/test-source-map-consumer.js
+++ b/test/test-source-map-consumer.js
@@ -88,6 +88,17 @@ exports["test that the `sources` field has the original sources"] =
     map.destroy();
   };
 
+exports["test that the SourceMapConsumer supports the ignoreList"] =
+  async function (assert) {
+    const map = await new SourceMapConsumer(util.testMapWithIgnoreList);
+    const sources = map.sources;
+    const ignoreList = map.x_google_ignoreList;
+    assert.equal(ignoreList.length, 1);
+    assert.equal(ignoreList[0], 0);
+    assert.equal(sources[ignoreList[0]], "/the/root/one.js");
+    map.destroy();
+  };
+
 exports["test that the source root is reflected in a mapping's source field"] =
   async function (assert) {
     let map;
diff --git a/test/util.js b/test/util.js
index fe2fc641..d99669c3 100644
--- a/test/util.js
+++ b/test/util.js
@@ -37,6 +37,18 @@ exports.testMap = {
   mappings:
     "CAAC,IAAI,IAAM,SAAUA,GAClB,OAAOC,IAAID;CCDb,IAAI,IAAM,SAAUE,GAClB,OAAOA",
 };
+
+exports.testMapWithIgnoreList = {
+  version: 3,
+  file: "min.js",
+  names: ["bar", "baz", "n"],
+  sources: ["one.js", "two.js"],
+  sourceRoot: "/the/root",
+  mappings:
+    "CAAC,IAAI,IAAM,SAAUA,GAClB,OAAOC,IAAID;CCDb,IAAI,IAAM,SAAUE,GAClB,OAAOA",
+  x_google_ignoreList: [0],
+};
+
 exports.testMapNoSourceRoot = {
   version: 3,
   file: "min.js",
diff --git a/wasm-mappings/.DS_Store b/wasm-mappings/.DS_Store
new file mode 100644
index 00000000..b30e622b
Binary files /dev/null and b/wasm-mappings/.DS_Store differ