diff --git a/lib/src/cache.dart b/lib/src/cache.dart
index 1073d361..1124437a 100644
--- a/lib/src/cache.dart
+++ b/lib/src/cache.dart
@@ -1,6 +1,7 @@
 import 'dart:async';
 import 'package:angel_framework/angel_framework.dart';
 import 'package:intl/intl.dart';
+import 'package:pool/pool.dart';
 
 final DateFormat _fmt = new DateFormat('EEE, d MMM yyyy HH:mm:ss');
 
@@ -14,12 +15,16 @@ class ResponseCache {
 
   ResponseCache({this.timeout});
 
+  /// Removes an entry from the response cache.
+  void invalidate(String path) => _cache.remove(path);
+
   /// A middleware that handles requests with an `If-Modified-Since` header.
   ///
   /// This prevents the server from even having to access the cache, and plays very well with static assets.
   Future<bool> ifModifiedSince(RequestContext req, ResponseContext res) async {
     if (req.headers.value('if-modified-since') != null) {
-      var modifiedSince = _fmt.parse(req.headers.value('if-modified-since'));
+      var modifiedSince = _fmt
+          .parse(req.headers.value('if-modified-since').replaceAll('GMT', ''));
 
       // Check if there is a cache entry.
       for (var pattern in patterns) {
@@ -38,11 +43,30 @@ class ResponseCache {
     return true;
   }
 
+  /// A response finalizer that saves responses to the cache.
   Future<bool> responseFinalizer(
       RequestContext req, ResponseContext res) async {
     if (res.statusCode == 304) return true;
 
-    var now = new DateTime.now().toUtc();
+    // Check if there is a cache entry.
+    for (var pattern in patterns) {
+      if (pattern.allMatches(req.uri.path).isNotEmpty) {
+        var now = new DateTime.now().toUtc();
+
+        // Invalidate the response, if need be.
+        if (_cache.containsKey(req.uri.path)) {
+          // If there is no timeout, don't invalidate.
+          if (timeout == null) return true;
+
+          // Otherwise, don't invalidate unless the timeout has been exceeded.
+          var response = _cache[req.uri.path];
+          if (now.difference(response.timestamp) < timeout) return true;
+
+          // If the cache entry should be invalidated, then invalidate it.
+          invalidate(req.uri.path);
+        }
+      }
+    }
   }
 
   void setCachedHeaders(
diff --git a/pubspec.yaml b/pubspec.yaml
index 091d738c..d06ce879 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -3,6 +3,7 @@ dependencies:
   angel_framework: ">=1.0.0-dev <2.0.0"
   intl: ^0.15.0
   meta: ^1.0.0
+  pool: ^1.0.0
 dev_dependencies:
   angel_test: ^1.1.0
   glob: ^1.0.0