diff --git a/.npmignore b/.npmignore
new file mode 100644
index 0000000..e07b503
--- /dev/null
+++ b/.npmignore
@@ -0,0 +1,6 @@
+.travis.yml
+.vscode/
+.nyc_output/
+test/
+example/
+coverage/
diff --git a/index.js b/index.js
index 9ec7448..ac30787 100644
--- a/index.js
+++ b/index.js
@@ -48,6 +48,10 @@ function extendError(AWS, opts) {
   const origSend = AWS.Request.prototype.send;
 
   AWS.Request.prototype.send = function sendEx(callback) {
+    if (!callback) {
+      return origSend.call(this)
+    }
+
     const req = this;
     let runStack = null;
     if (needRunAt) runStack = getRunStack(arguments.callee).slice(2);
diff --git a/package.json b/package.json
index 7ecd090..45cd090 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "extend-aws-error",
-  "version": "0.5.0",
+  "version": "0.6.0",
   "description": "Extend AWS SDK request error with the request information",
   "main": "extend_aws_error.js",
   "scripts": {