diff --git a/packages/zone.js/dist/BUILD.bazel b/packages/zone.js/dist/BUILD.bazel
index 2ab724db22..dbbe26a88a 100644
--- a/packages/zone.js/dist/BUILD.bazel
+++ b/packages/zone.js/dist/BUILD.bazel
@@ -100,6 +100,8 @@ genrule(
         ],
         cmd = " && ".join([
             "mkdir -p $(@D)",
+            # remove the last line '//# sourceMappingURL=b[0].umd.js.map' because we don't release
+            # source map for now
             "sed '$$d' $(@D)/" + b[0].replace("-", "_") + "_rollup.es5umd.js > $(@D)/" + b[0] + ".js",
             "cp $(@D)/" + b[0].replace("-", "_") + "_rollup.min.es5umd.js $(@D)/" + b[0] + ".min.js",
         ]),
@@ -174,6 +176,8 @@ genrule(
         ],
         cmd = " && ".join([
             "mkdir -p $(@D)",
+            # remove the last line '//# sourceMappingURL=b[0].umd.js.map' because we don't release
+            # source map for now
             "sed '$$d' $(@D)/" + b.replace("-", "_") + "_rollup.umd.js > $(@D)/" + b + ".js",
             "cp $(@D)/" + b.replace("-", "_") + "_rollup.min.umd.js $(@D)/" + b + ".min.js",
         ]),
diff --git a/packages/zone.js/test/npm_package/npm_package.spec.ts b/packages/zone.js/test/npm_package/npm_package.spec.ts
index 1c9de06332..b4414ad9cd 100644
--- a/packages/zone.js/test/npm_package/npm_package.spec.ts
+++ b/packages/zone.js/test/npm_package/npm_package.spec.ts
@@ -49,11 +49,16 @@ describe('Zone.js npm_package', () => {
     describe('es5', () => {
       it('zone.js(es5) should not contain es6 spread code',
          () => { expect(shx.cat('zone.js')).not.toContain('let value of values'); });
+
+      it('zone.js(es5) should not contain source map comment',
+         () => { expect(shx.cat('zone.js')).not.toContain('sourceMappingURL'); });
     });
 
     describe('es2015', () => {
       it('zone-evergreen.js(es2015) should contain es6 code',
          () => { expect(shx.cat('zone-evergreen.js')).toContain('let value of values'); });
+      it('zone.js(es5) should not contain source map comment',
+         () => { expect(shx.cat('zone-evergreen.js')).not.toContain('sourceMappingURL'); });
     });
 
     describe('dist file list', () => {