diff --git a/docs/config/02-files.md b/docs/config/02-files.md
index 81712c4ab..9b1021da2 100644
--- a/docs/config/02-files.md
+++ b/docs/config/02-files.md
@@ -41,6 +41,11 @@ Each pattern is either a simple string or an object with four properties:
 * **Default.** `true`
 * **Description.** Should the files be served by Karma's webserver?
 
+### `nocache`
+* **Type.** Boolean
+* **Default.** `false`
+* **Description.** Should the files be served from disk on each request by Karma's webserver?
+
 
 ## Preprocessor transformations
 Depending on preprocessor configuration, be aware that files loaded may be transformed and no longer available in
@@ -62,7 +67,10 @@ files: [
   {pattern: 'compiled/index.html', watched: false},
 
   // this file only gets watched and is otherwise ignored
-  {pattern: 'app/index.html', included: false, served: false}
+  {pattern: 'app/index.html', included: false, served: false},
+
+  // this file will be served on demand from disk and will be ignored by the watcher
+  {pattern: 'compiled/app.js.map', included: false, served: true, watched: false, nocache: true}
 ],
 ```
 
@@ -73,7 +81,7 @@ Example for loading images
 
 ```javascript
 files: [
-  {pattern: "test/images/*.jpg", watched: false, included: false, served: true}
+  {pattern: 'test/images/*.jpg', watched: false, included: false, served: true, nocache: false}
 ],
 ```
 
diff --git a/lib/config.js b/lib/config.js
index 02cd8ec36..5f9302dfa 100644
--- a/lib/config.js
+++ b/lib/config.js
@@ -22,15 +22,16 @@ try {
   LIVE_SCRIPT_AVAILABLE = true;
 } catch (e) {}
 
-var Pattern = function(pattern, served, included, watched) {
+var Pattern = function(pattern, served, included, watched, nocache) {
   this.pattern = pattern;
   this.served = helper.isDefined(served) ? served : true;
   this.included = helper.isDefined(included) ? included : true;
   this.watched = helper.isDefined(watched) ? watched : true;
+  this.nocache = helper.isDefined(nocache) ? nocache : false;
 };
 
 var UrlPattern = function(url) {
-  Pattern.call(this, url, false, true, false);
+  Pattern.call(this, url, false, true, false, false);
 };
 
 
@@ -43,15 +44,20 @@ var createPatternObject = function(pattern) {
     if (pattern.pattern && helper.isString(pattern.pattern)) {
       return helper.isUrlAbsolute(pattern.pattern) ?
         new UrlPattern(pattern.pattern) :
-        new Pattern(pattern.pattern, pattern.served, pattern.included, pattern.watched);
+        new Pattern(
+          pattern.pattern,
+          pattern.served,
+          pattern.included,
+          pattern.watched,
+          pattern.nocache);
     }
 
     log.warn('Invalid pattern %s!\n\tObject is missing "pattern" property.', pattern);
-    return new Pattern(null, false, false, false);
+    return new Pattern(null, false, false, false, false);
   }
 
   log.warn('Invalid pattern %s!\n\tExpected string or object with "pattern" property.', pattern);
-  return new Pattern(null, false, false, false);
+  return new Pattern(null, false, false, false, false);
 };
 
 
diff --git a/lib/file_list.js b/lib/file_list.js
index 9b33ddb56..9c10260be 100644
--- a/lib/file_list.js
+++ b/lib/file_list.js
@@ -32,6 +32,8 @@ var File = function(path, mtime) {
 
   this.mtime = mtime;
   this.isUrl = false;
+
+  this.doNotCache = false;
 };
 
 var Url = function(path) {
@@ -102,6 +104,10 @@ var List = function(patterns, excludes, emitter, preprocess, batchInterval) {
             files.included.push(file);
           }
 
+          if (patterns[idx].nocache) {
+            file.doNotCache = true;
+          }
+
           uniqueMap[file.path] = true;
         }
       });
@@ -216,15 +222,24 @@ var List = function(patterns, excludes, emitter, preprocess, batchInterval) {
                 // TODO(vojta): reuse file objects
                 var file = new File(path, stat.mtime);
 
-                preprocess(file, function(err) {
-                  buckets[i].push(file);
+                if (patternObject.nocache) {
+                  log.debug('Not preprocessing "%s" due to nocache', path);
 
-                  if (err) {
-                    addError(path);
-                  }
+                  file.doNotCache = true;
+                  buckets[i].push(file);
 
                   finish();
-                });
+                } else {
+                  preprocess(file, function(err) {
+                    buckets[i].push(file);
+
+                    if (err) {
+                      addError(path);
+                    }
+
+                    finish();
+                  });
+                }
               } else {
                 log.debug('Ignored directory "%s"', path);
                 finish();
diff --git a/lib/middleware/common.js b/lib/middleware/common.js
index 979efafee..6f0c40952 100644
--- a/lib/middleware/common.js
+++ b/lib/middleware/common.js
@@ -28,7 +28,7 @@ var serve404 = function(response, path) {
 var createServeFile = function(fs, directory) {
   var cache = Object.create(null);
 
-  return function(filepath, response, transform, content) {
+  return function(filepath, response, transform, content, doNotCache) {
     var responseData;
 
     if (directory) {
@@ -40,7 +40,7 @@ var createServeFile = function(fs, directory) {
     }
 
     // serve from cache
-    if (content) {
+    if (content && !doNotCache) {
       response.setHeader('Content-Type', mime.lookup(filepath, 'text/plain'));
 
       // call custom transform fn to transform the data
@@ -57,7 +57,9 @@ var createServeFile = function(fs, directory) {
         return serve404(response, filepath);
       }
 
-      cache[filepath] = data.toString();
+      if (!doNotCache) {
+        cache[filepath] = data.toString();
+      }
 
       response.setHeader('Content-Type', mime.lookup(filepath, 'text/plain'));
 
diff --git a/lib/middleware/source_files.js b/lib/middleware/source_files.js
index e20f4d16f..7ef6e1c4f 100644
--- a/lib/middleware/source_files.js
+++ b/lib/middleware/source_files.js
@@ -46,7 +46,7 @@ var createSourceFilesMiddleware = function(filesPromise, serveFile,
             // without timestamps - no cache (debug)
             common.setNoCacheHeaders(response);
           }
-        }, file.content);
+        }, file.content, file.doNotCache);
       } else {
         next();
       }
diff --git a/test/unit/file_list.spec.coffee b/test/unit/file_list.spec.coffee
index 00ee4097c..10992455a 100644
--- a/test/unit/file_list.spec.coffee
+++ b/test/unit/file_list.spec.coffee
@@ -241,6 +241,20 @@ describe 'file_list', ->
         expect(pathsFrom files.served).to.deep.equal ['/a.txt']
         done()
 
+    it 'should properly mark files that should not be cached', (done) ->
+      # /a.*       => /a.txt                   [nocache FALSE]
+      # /some/*.js => /some/a.js, /some/b.js   [nocache TRUE]
+      files = [new config.Pattern('/a.*'), new config.Pattern('/some/*.js', true, true, true, true)]
+      list = new m.List files, [], emitter, preprocessMock
+
+      refreshListAndThen (files) ->
+        expect(pathsFrom files.served).to.deep.equal ['/a.txt', '/some/a.js', '/some/b.js']
+        expect(preprocessMock.callCount).to.equal 1
+        expect(files.served[0].doNotCache).to.be.false
+        expect(files.served[1].doNotCache).to.be.true
+        expect(files.served[2].doNotCache).to.be.true
+        done()
+
 
   #============================================================================
   # List.getIncludedFiles()
diff --git a/test/unit/middleware/source_files.spec.coffee b/test/unit/middleware/source_files.spec.coffee
index fdb40b33c..455eb3b64 100644
--- a/test/unit/middleware/source_files.spec.coffee
+++ b/test/unit/middleware/source_files.spec.coffee
@@ -174,3 +174,19 @@ describe 'middleware.source_files', ->
       done()
 
     callHandlerWith '/absolute/some/file.js'
+
+  it 'should not use cached content if doNotCache is set', (done) ->
+    cachedFile = new File('/src/some.js')
+    cachedFile.content = 'cached-content'
+    cachedFile.doNotCache = true
+
+    servedFiles [
+      cachedFile
+    ]
+
+    response.once 'end', ->
+      expect(nextSpy).not.to.have.been.called
+      expect(response).to.beServedAs 200, 'js-source'
+      done()
+
+    callHandlerWith '/absolute/src/some.js'