diff --git a/boost.api.inc b/boost.api.inc
index 2313a24c63efbaf468b647d310d2c10a87ee00c7..5fd192537a5694b3ad7848dbd8603148bd1aa411 100644
--- a/boost.api.inc
+++ b/boost.api.inc
@@ -43,6 +43,18 @@ function boost_is_cacheable($path) {
   return !(BOOST_CACHEABILITY_OPTION xor preg_match($regexp, $alias));
 }
 
+/**
+ * Determines whether a given Drupal page is currently cached or not.
+ */
+function boost_is_cached($path) {
+  $path = (empty($path) ? BOOST_FRONTPAGE : $path);
+  $alias = drupal_get_path_alias($path);
+  $path = drupal_get_normal_path($path); // normalize path
+
+  // TODO: also determine if alias/symlink exists?
+  return file_exists(boost_file_path($path));
+}
+
 /**
  * Deletes all static files currently in the cache.
  */
diff --git a/boost.module b/boost.module
index 0c13cb73e3da4bb7ee861a6e307c7e20bce46ec9..68998ceb6ef8e3f0b314d17f6e6239035ae84ad3 100644
--- a/boost.module
+++ b/boost.module
@@ -114,6 +114,47 @@ function boost_init() {
   }
 }
 
+/**
+ * Implementation of hook_exit(). Performs cleanup tasks.
+ *
+ * For POST requests by anonymous visitors, this adds a dummy query string
+ * to any URL being redirected to using drupal_goto().
+ *
+ * This is pretty much a hack that assumes a bit too much familiarity with
+ * what happens under the hood of the Drupal core function drupal_goto().
+ *
+ * It's necessary, though, in order for any session messages set on form
+ * submission to actually show up on the next page if that page has been
+ * cached by Boost.
+ */
+function boost_exit($destination = NULL) {
+  // Check that hook_exit() was invoked by drupal_goto() for a POST request:
+  if (!empty($destination) && $_SERVER['REQUEST_METHOD'] == 'POST') {
+
+    // Check that we're dealing with an anonymous visitor. and that some
+    // session messages have actually been set during this page request:
+    global $user;
+    if (empty($user->uid) && ($messages = drupal_set_message())) {
+
+      // Check that the page we're redirecting to has been cached by Boost
+      // and really necessitates special handling:
+      extract(parse_url($destination));
+      $path = ($path == base_path() ? '' : substr($path, strlen(base_path())));
+      if (boost_is_cached($path) && empty($query)) {
+        // FIXME: call any remaining exit hooks since we're about to terminate.
+
+        // Add a query string to ensure we don't serve a static copy of
+        // the page we're redirecting to, which would prevent the session
+        // messages from showing up:
+        $destination = url($path, 't=' . time(), $fragment, TRUE);
+
+        // Do what drupal_goto() would do if we were to return to it:
+        exit(header('Location: ' . $destination));
+      }
+    }
+  }
+}
+
 /**
  * Implementation of hook_form_alter(). Performs alterations before a form
  * is rendered.