diff --git a/README.md b/README.md
index 1c3d42c..594ff47 100644
--- a/README.md
+++ b/README.md
@@ -16,7 +16,10 @@ All options are optional.
 
 * `dogstatsd` node-dogstatsd client. `default = new (require("node-dogstatsd")).StatsD()`
 * `stat` *string* name for the stat. `default = "node.express.router"`
-* `tags` *array* of tags to be added to the histogram. `default = []`
+* `tags` either:
+	* *array* of tags to be added to the histogram
+	* *function* that takes `req` and `res`, returning an array of tags
+	* `default = []`
 * `path` *boolean* include path tag. `default = false`
 * `method` *boolean* include http method tag. `default = false`
 * `protocol` *boolean* include protocol tag. `default = false`
diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..0d38be6
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,9 @@
+import { RequestHandler } from 'express'
+
+// name 'connectDatadog' doesn't really matter
+// Just make sure that the function and namespace below have the same names
+declare function connectDatadog(options: any): RequestHandler
+declare namespace connectDatadog {
+
+}
+export = connectDatadog
diff --git a/lib/index.js b/lib/index.js
index dd47dbf..1dd678d 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -25,7 +25,7 @@ module.exports = function (options) {
 			var baseUrl = (base_url !== false) ? req.baseUrl : '';
 			var statTags = [
 				"route:" + baseUrl + req.route.path
-			].concat(tags);
+			].concat(typeof tags === 'function' ? tags(req, res) : tags);
 
 			if (options.method) {
 				statTags.push("method:" + req.method.toLowerCase());
diff --git a/package.json b/package.json
index 34d32f3..dc70df6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "connect-datadog",
-	"version": "0.0.6",
+	"version": "0.0.7",
 	"description": "Datadog middleware for Connect JS / Express",
 	"main": "index.js",
 	"repository": {
@@ -15,6 +15,10 @@
 	"license": "MIT",
 	"readmeFilename": "README.md",
 	"dependencies": {
+		"express": "^4.16.3",
 		"node-dogstatsd": "0.0.6"
+	},
+	"devDependencies": {
+		"@types/express": "^4.16.0"
 	}
 }