diff --git a/baselines/requireJquery.d.ts b/baselines/requireJquery.d.ts
new file mode 100644
index 0000000..7d80676
--- /dev/null
+++ b/baselines/requireJquery.d.ts
@@ -0,0 +1,5 @@
+declare namespace requireJquery {
+    function jqeury(w: any): any;
+
+}
+
diff --git a/baselines/simple.d.ts b/baselines/simple.d.ts
new file mode 100644
index 0000000..00f3327
--- /dev/null
+++ b/baselines/simple.d.ts
@@ -0,0 +1,4 @@
+declare const simple: {
+    test: number;
+};
+
diff --git a/lib/run.ts b/lib/run.ts
index 95ef897..e20be44 100644
--- a/lib/run.ts
+++ b/lib/run.ts
@@ -83,8 +83,7 @@ try {
         const filename = args['expression-file'];
         name = path.basename(filename, path.extname(filename)).replace(/[^A-Za-z0-9]/g, '_');
         (module as any).paths.unshift(process.cwd() + '/node_modules');
-        const fileContent = fs.readFileSync(filename, "utf-8");
-        result = guess.generateIdentifierDeclarationFile(name, eval(fileContent));
+        result = guess.generateIdentifierDeclarationFile(name, require(path.resolve(filename)));
     } else if (args.identifier) {
         if (args.name) throw new ArgsError('Cannot use --name with --identifier');
         if (args.module || args.expression) throw new ArgsError('Cannot specify more than one input');
diff --git a/package.json b/package.json
index 3f242d8..8621532 100644
--- a/package.json
+++ b/package.json
@@ -22,6 +22,7 @@
     "lodash": "latest",
     "mocha": "^3.0.2",
     "react": "latest",
+    "shx": "^0.3.3",
     "tslint": "^5.1.0",
     "webpack": "^1.13.1"
   },
@@ -30,7 +31,7 @@
   ],
   "preferGlobal": true,
   "scripts": {
-    "test": "mocha bin/tests/test.js",
+    "test": "shx cp -r ./tests/fixtures/ ./bin/tests && mocha bin/tests/test.js",
     "build": "tsc",
     "build-browser": "tsc -p browser && webpack",
     "lint": "tslint --project tsconfig.json --format stylish"
diff --git a/tests/fixtures/require-jquery.js b/tests/fixtures/require-jquery.js
new file mode 100644
index 0000000..cf23b31
--- /dev/null
+++ b/tests/fixtures/require-jquery.js
@@ -0,0 +1,3 @@
+const jqeury = require("jquery")
+
+exports.jqeury = jqeury;
diff --git a/tests/fixtures/simple.js b/tests/fixtures/simple.js
new file mode 100644
index 0000000..d154606
--- /dev/null
+++ b/tests/fixtures/simple.js
@@ -0,0 +1 @@
+exports.test = 1
diff --git a/tests/test.ts b/tests/test.ts
index 9e4c985..650a54e 100644
--- a/tests/test.ts
+++ b/tests/test.ts
@@ -44,6 +44,11 @@ const expressions: { [s: string]: any } = {
     overriddenToString,
 };
 
+const expressionFiles: { [s: string]: any } = {
+    simple: path.join(__dirname, "fixtures", "simple.js"),
+    requireJquery: path.join(__dirname, "fixtures", "require-jquery.js"),
+};
+
 function checkDeclarationBaseline(name: string, content: string) {
     const filename = path.join(__dirname, `../../baselines/${name}`);
     const existing = fs.existsSync(filename) ? fs.readFileSync(filename, 'utf-8') : '<none>';
@@ -70,3 +75,12 @@ describe("Expression tests", () => {
         });
     }
 });
+
+describe("Expression file test", () => {
+    for (const key of Object.keys(expressionFiles)) {
+        it(`Generates the same declaration for ${key}`, () => {
+            const result = tsg.generateIdentifierDeclarationFile(key!, require(expressionFiles[key!]));
+            checkDeclarationBaseline(`${key}.d.ts`, result);
+        });
+    }
+});