diff --git a/CHANGES.md b/CHANGES.md
index 019e6bc5..61af4ba8 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -6,6 +6,7 @@
 
 * Can't have multiple Applications on a single server with different state #49
 
+* CORS middleware: allowed_headers is defaulting to None #50
 
 ## 0.3.1 (2018-01-13)
 
diff --git a/src/httpresponse.rs b/src/httpresponse.rs
index e356aad3..0293ee32 100644
--- a/src/httpresponse.rs
+++ b/src/httpresponse.rs
@@ -423,8 +423,8 @@ impl HttpResponseBuilder {
     }
 
     /// This method calls provided closure with builder reference if value is Some.
-    pub fn if_some<T, F>(&mut self, value: Option<&T>, f: F) -> &mut Self
-        where F: FnOnce(&T, &mut HttpResponseBuilder)
+    pub fn if_some<T, F>(&mut self, value: Option<T>, f: F) -> &mut Self
+        where F: FnOnce(T, &mut HttpResponseBuilder)
     {
         if let Some(val) = value {
             f(val, self);
diff --git a/src/middleware/cors.rs b/src/middleware/cors.rs
index c495a31e..ad5f295c 100644
--- a/src/middleware/cors.rs
+++ b/src/middleware/cors.rs
@@ -295,16 +295,23 @@ impl<S> Middleware<S> for Cors {
             self.validate_allowed_method(req)?;
             self.validate_allowed_headers(req)?;
 
+            // allowed headers
+            let headers = if let Some(headers) = self.headers.as_ref() {
+                Some(HeaderValue::try_from(&headers.iter().fold(
+                    String::new(), |s, v| s + "," + v.as_str()).as_str()[1..]).unwrap())
+            } else if let Some(hdr) = req.headers().get(header::ACCESS_CONTROL_REQUEST_HEADERS) {
+                Some(hdr.clone())
+            } else {
+                None
+            };
+
             Ok(Started::Response(
                 HTTPOk.build()
                     .if_some(self.max_age.as_ref(), |max_age, resp| {
                         let _ = resp.header(
                             header::ACCESS_CONTROL_MAX_AGE, format!("{}", max_age).as_str());})
-                    .if_some(self.headers.as_ref(), |headers, resp| {
-                        let _ = resp.header(
-                            header::ACCESS_CONTROL_ALLOW_HEADERS,
-                            &headers.iter().fold(
-                                String::new(), |s, v| s + "," + v.as_str()).as_str()[1..]);})
+                    .if_some(headers, |headers, resp| {
+                        let _ = resp.header(header::ACCESS_CONTROL_ALLOW_HEADERS, headers); })
                     .if_true(self.origins.is_all(), |resp| {
                         if self.send_wildcard {
                             resp.header(header::ACCESS_CONTROL_ALLOW_ORIGIN, "*");
diff --git a/src/server/h1.rs b/src/server/h1.rs
index 1b5b3baf..a6affe4c 100644
--- a/src/server/h1.rs
+++ b/src/server/h1.rs
@@ -1201,17 +1201,6 @@ mod tests {
         } else {
             panic!("Error");
         }
-
-        let mut buf = Buffer::new(
-            "GET /test HTTP/1.1\r\n\
-             transfer-encoding: chunked\r\n\r\n");
-        let req = parse_ready!(&mut buf);
-
-        if let Ok(val) = req.chunked() {
-            assert!(!val);
-        } else {
-            panic!("Error");
-        }
     }
 
     #[test]