diff --git a/lib/source-map-consumer.js b/lib/source-map-consumer.js
index 17ef92b1..4a4f295b 100644
--- a/lib/source-map-consumer.js
+++ b/lib/source-map-consumer.js
@@ -859,7 +859,7 @@ class IndexedSourceMapConsumer extends SourceMapConsumer {
       const section = this._sections[i];
 
       const content = section.consumer.sourceContentFor(aSource, true);
-      if (content) {
+      if (content != null) {
         return content;
       }
     }
diff --git a/test/test-indexed-empty-source-content.js b/test/test-indexed-empty-source-content.js
new file mode 100644
index 00000000..72bc83fb
--- /dev/null
+++ b/test/test-indexed-empty-source-content.js
@@ -0,0 +1,143 @@
+/* -*- Mode: js; js-indent-level: 2; -*- */
+/*
+ * Copyright 2011 Mozilla Foundation and contributors
+ * Licensed under the New BSD license. See LICENSE or:
+ * http://opensource.org/licenses/BSD-3-Clause
+ */
+
+const SourceMapConsumer =
+  require("../lib/source-map-consumer").SourceMapConsumer;
+const SourceMapGenerator =
+  require("../lib/source-map-generator").SourceMapGenerator;
+
+function issue420Map() {
+  return {
+    version: 3,
+    sections: [
+      {
+        offset: { line: 0, column: 0 },
+        map: {
+          version: 3,
+          sources: ["123", "456"],
+          sourcesContent: ["a\nb\nc\n", ""],
+          mappings: "AAAA;AACA;AACA;",
+        },
+      },
+    ],
+  };
+}
+
+exports["test indexed sourceContentFor retains an empty source"] = async function (assert) {
+  const consumer = await new SourceMapConsumer(issue420Map());
+  try {
+    assert.strictEqual(consumer.sourceContentFor("456"), "");
+  } finally {
+    consumer.destroy();
+  }
+};
+
+exports["test fromSourceMap retains empty indexed source content"] = async function (assert) {
+  const consumer = await new SourceMapConsumer(issue420Map());
+  try {
+    // No artificial sourceRoot assignment: exercise the current public path.
+    const result = SourceMapGenerator.fromSourceMap(consumer).toJSON();
+    const nonemptyIndex = result.sources.indexOf("123");
+    const emptyIndex = result.sources.indexOf("456");
+    assert.ok(nonemptyIndex >= 0);
+    assert.ok(emptyIndex >= 0);
+    assert.strictEqual(result.sourcesContent[nonemptyIndex], "a\nb\nc\n");
+    assert.strictEqual(result.sourcesContent[emptyIndex], "");
+    assert.strictEqual(result.mappings, "AAAA;AACA;AACA");
+  } finally {
+    consumer.destroy();
+  }
+};
+
+exports["test indexed lookup continues past a section without the source"] = async function (assert) {
+  const map = issue420Map();
+  map.sections.unshift({
+    offset: { line: 0, column: 0 },
+    map: {
+      version: 3,
+      names: [],
+      sources: ["other.js"],
+      sourcesContent: ["other content"],
+      mappings: "AAAA",
+    },
+  });
+  map.sections[1].offset = { line: 1, column: 0 };
+  const consumer = await new SourceMapConsumer(map);
+  try {
+    assert.strictEqual(consumer.sourceContentFor("other.js"), "other content");
+    assert.strictEqual(consumer.sourceContentFor("456"), "");
+  } finally {
+    consumer.destroy();
+  }
+};
+
+exports["test nested indexed maps retain empty source content"] = async function (assert) {
+  const consumer = await new SourceMapConsumer({
+    version: 3,
+    sections: [
+      { offset: { line: 0, column: 0 }, map: issue420Map() },
+    ],
+  });
+  try {
+    assert.strictEqual(consumer.sourceContentFor("456"), "");
+    const result = SourceMapGenerator.fromSourceMap(consumer).toJSON();
+    const index = result.sources.indexOf("456");
+    assert.ok(index >= 0);
+    assert.strictEqual(result.sourcesContent[index], "");
+  } finally {
+    consumer.destroy();
+  }
+};
+
+exports["test nullOnMissing does not discard present empty content"] = async function (assert) {
+  const consumer = await new SourceMapConsumer(issue420Map());
+  try {
+    assert.strictEqual(consumer.sourceContentFor("456", true), "");
+  } finally {
+    consumer.destroy();
+  }
+};
+
+exports["test basic consumer and generator retain empty source content"] = async function (assert) {
+  const consumer = await new SourceMapConsumer(issue420Map().sections[0].map);
+  try {
+    assert.strictEqual(consumer.sourceContentFor("456"), "");
+    const result = SourceMapGenerator.fromSourceMap(consumer).toJSON();
+    const index = result.sources.indexOf("456");
+    assert.ok(index >= 0);
+    assert.strictEqual(result.sourcesContent[index], "");
+  } finally {
+    consumer.destroy();
+  }
+};
+
+exports["test indexed nonempty source content conversion is unchanged"] = async function (assert) {
+  const map = issue420Map();
+  map.sections[0].map.sourcesContent[1] = "nonempty second source";
+  const consumer = await new SourceMapConsumer(map);
+  try {
+    assert.strictEqual(consumer.sourceContentFor("456"), "nonempty second source");
+    const result = SourceMapGenerator.fromSourceMap(consumer).toJSON();
+    const index = result.sources.indexOf("456");
+    assert.ok(index >= 0);
+    assert.strictEqual(result.sourcesContent[index], "nonempty second source");
+  } finally {
+    consumer.destroy();
+  }
+};
+
+exports["test genuinely missing indexed source retains nullOnMissing behavior"] = async function (assert) {
+  const consumer = await new SourceMapConsumer(issue420Map());
+  try {
+    assert.strictEqual(consumer.sourceContentFor("missing.js", true), null);
+    assert.throws(function () {
+      consumer.sourceContentFor("missing.js");
+    }, /not in the SourceMap/);
+  } finally {
+    consumer.destroy();
+  }
+};