diff --git a/ring-core/src/ring/middleware/not_modified.clj b/ring-core/src/ring/middleware/not_modified.clj
index be0e1fc8..47ad5d0f 100644
--- a/ring-core/src/ring/middleware/not_modified.clj
+++ b/ring-core/src/ring/middleware/not_modified.clj
@@ -2,14 +2,15 @@
   "Middleware to return a 304 Not Modified response."
   (:use [ring.util.time :only (parse-date)]
         [ring.util.response :only (status)]
-        [ring.util.io :only (close!)]))
+        [ring.util.io :only (close!)]
+        [ring.util.headers :only (get-header)]))
 
 (defn- etag-match? [request response]
   (if-let [etag (get-in response [:headers "etag"])]
     (= etag (get-in request [:headers "if-none-match"]))))
 
 (defn- ^java.util.Date date-header [response header]
-  (if-let [http-date (get-in response [:headers header])]
+  (if-let [http-date (get-header response header)]
     (parse-date http-date)))
 
 (defn- not-modified-since? [request response]
diff --git a/ring-core/src/ring/util/headers.clj b/ring-core/src/ring/util/headers.clj
new file mode 100644
index 00000000..098ada63
--- /dev/null
+++ b/ring-core/src/ring/util/headers.clj
@@ -0,0 +1,12 @@
+(ns ring.util.headers)
+
+(defn get-header 
+  "Get request or response header by name.
+   Lookup is case-insensitive"
+  [message header-name]
+  (let [normalized-name (.toLowerCase header-name)]
+    (-> (filter
+          #(= (-> % first .toLowerCase) normalized-name) 
+          (:headers message))
+      first
+      second)))
\ No newline at end of file
diff --git a/ring-core/test/ring/util/test/headers.clj b/ring-core/test/ring/util/test/headers.clj
new file mode 100644
index 00000000..c3463aa0
--- /dev/null
+++ b/ring-core/test/ring/util/test/headers.clj
@@ -0,0 +1,7 @@
+(ns ring.util.test.headers
+  (:use ring.util.headers
+        clojure.test))
+
+(deftest test-get-header
+  (is (= "a" (get-header {:headers {"Some-Header" "a"}} "some-header")))
+  (is (nil? (get-header {:headers {"Same-Hero" "a"}} "some-header"))))
\ No newline at end of file