diff --git a/mollom.module b/mollom.module
index 0113c5f..50fcb58 100644
--- a/mollom.module
+++ b/mollom.module
@@ -726,9 +726,6 @@ function mollom_form_alter(&$form, &$form_state, $form_id) {
         '#weight' => (isset($form['actions']['#weight']) ? $form['actions']['#weight'] - 1 : 99),
         '#tree' => TRUE,
       );
-      // Enable caching of this form; required for our form validation and
-      // submit handlers.
-      $form_state['cache'] = TRUE;
 
       // Add Mollom form validation handlers.
       // Form-level validation handlers are required, since we need access to
@@ -1464,7 +1461,9 @@ function _mollom_status($reset = FALSE) {
  * Outputs a warning message about enabled testing mode (once).
  */
 function _mollom_testing_mode_warning() {
-  $warned = &drupal_static(__FUNCTION__);
+  // drupal_set_message() starts a session and disables page caching, which
+  // breaks testing. Therefore, tests set the verbose variable to TRUE.
+  $warned = &drupal_static(__FUNCTION__, variable_get('mollom_testing_mode_omit_warning', NULL));
   if (isset($warned)) {
     return;
   }
@@ -1527,6 +1526,7 @@ function mollom_element_info() {
       '#process' => array(
         'mollom_process_mollom',
       ),
+      '#pre_render' => array('mollom_pre_render_mollom'),
     ),
   );
 }
@@ -1562,10 +1562,6 @@ function mollom_process_mollom($element, &$form_state, $complete_form) {
     'response' => array(
     ),
   );
-  // Instantiate a new Mollom class, unless there is not a cached one.
-  if (!isset($form_state['mollom']['class'])) {
-    $form_state['mollom']['class'] = mollom();
-  }
   // Add remaining information about the registered form.
   $form_state['mollom'] += $element['#mollom_form'];
 
@@ -1594,7 +1590,6 @@ function mollom_process_mollom($element, &$form_state, $complete_form) {
   );
   $element['contentId'] = array(
     '#type' => 'hidden',
-    '#default_value' => isset($form_state['mollom']['response']['content']['id']) ? $form_state['mollom']['response']['content']['id'] : '',
     '#attributes' => array('class' => 'mollom-content-id'),
   );
   $element['captchaId'] = array(
@@ -1616,11 +1611,11 @@ function mollom_process_mollom($element, &$form_state, $complete_form) {
   );
   $element['spamScore'] = $data_spec;
   $element['spamClassification'] = $data_spec;
-  $element['solved'] = $data_spec;
   $element['qualityScore'] = $data_spec;
   $element['profanityScore'] = $data_spec;
-  $element['reason'] = $data_spec;
   $element['languages'] = $data_spec;
+  $element['reason'] = $data_spec;
+  $element['solved'] = $data_spec;
 
   // Add the CAPTCHA element.
   $element['captcha'] = array(
@@ -1635,14 +1630,16 @@ function mollom_process_mollom($element, &$form_state, $complete_form) {
   if (!variable_get('mollom_testing_mode', 0)) {
     $element['captcha']['#attributes']['autocomplete'] = 'off';
   }
-
   // Request and inject an initial CAPTCHA.
-  if ($form_state['mollom']['require_captcha'] && !$form_state['mollom']['passed_captcha'] && empty($form_state['mollom']['response']['captcha']['id'])) {
-    mollom_form_add_captcha($element, $form_state);
-  }
-  // If no CAPTCHA is required or it was solved already, hide the element.
-  elseif (!$form_state['mollom']['require_captcha'] || $form_state['mollom']['passed_captcha']) {
-    $element['captcha']['#access'] = FALSE;
+  if (!$form_state['mollom']['require_analysis'] && $form_state['mollom']['require_captcha']) {
+    if (!$form_state['mollom']['passed_captcha']) {
+      mollom_form_add_captcha($element, $form_state);
+      $form_state['cache'] = TRUE;
+    }
+    else {
+      // Only reached in case the form fully validated and is getting rebuilt.
+      $element['captcha']['#solved'] = TRUE;
+    }
   }
 
   // Add a spambot trap. Purposively use 'homepage' as field name.
@@ -1685,9 +1682,6 @@ function mollom_process_mollom($element, &$form_state, $complete_form) {
  *   The current state of the form. Passed by reference.
  */
 function mollom_form_add_captcha(&$element, &$form_state) {
-  // UX: Empty the CAPTCHA field value, as the user has to re-enter a new one.
-  $element['captcha']['#value'] = '';
-
   // Prevent the page cache from storing a form containing a CAPTCHA element.
   drupal_page_is_cacheable(FALSE);
 
@@ -1695,9 +1689,9 @@ function mollom_form_add_captcha(&$element, &$form_state) {
   // If we get a response, add the image CAPTCHA to the form element.
   if (!empty($captcha)) {
     $element['captcha']['#access'] = TRUE;
-    $element['captcha']['#required'] = TRUE;
     $element['captcha']['#field_prefix'] = $captcha;
-    // Assign the session ID returned by Mollom.
+
+    // Assign the new CAPTCHA ID returned by Mollom.
     $element['captchaId']['#value'] = $form_state['mollom']['response']['captcha']['id'];
     $form_state['values']['mollom']['captchaId'] = $form_state['mollom']['response']['captcha']['id'];
   }
@@ -1709,6 +1703,23 @@ function mollom_form_add_captcha(&$element, &$form_state) {
   }
 }
 
+function mollom_pre_render_mollom($element) {
+  if (empty($element['captchaId']['#value']) || !empty($element['captcha']['#solved'])) {
+    $element['captcha']['#access'] = FALSE;
+  }
+  else {
+    // The form element cannot be marked as #required, since _form_validate()
+    // would throw an element validation error on an empty value otherwise,
+    // before the form-level validation handler is executed.
+    // #access cannot default to FALSE, since the $form may be cached, and
+    // Form API ignores user input for all elements that are not accessible.
+    $element['captcha']['#required'] = TRUE;
+  }
+  // UX: Empty the CAPTCHA field value, as the user has to re-enter a new one.
+  $element['captcha']['#value'] = '';
+  return $element;
+}
+
 /**
  * Form validation handler to perform textual analysis of submitted form values.
  *
@@ -1737,8 +1748,8 @@ function mollom_validate_analysis(&$form, &$form_state) {
   if (isset($data['postId'])) {
     unset($data['postId']);
   }
-  if (isset($form_state['mollom']['response']['content']['id'])) {
-    $data['id'] = $form_state['mollom']['response']['content']['id'];
+  if (!empty($form_state['values']['mollom']['contentId'])) {
+    $data['id'] = $form_state['values']['mollom']['contentId'];
   }
   $data['checks'] = $form_state['mollom']['checks'];
   $data['strictness'] = $form_state['mollom']['strictness'];
@@ -1748,7 +1759,7 @@ function mollom_validate_analysis(&$form, &$form_state) {
   if (in_array('spam', $data['checks']) && $form_state['mollom']['unsure'] == 'binary') {
     $data['unsure'] = 0;
   }
-  $result = $form_state['mollom']['class']->checkContent($data);
+  $result = mollom()->checkContent($data);
 
   // Use all available data properties for log messages below.
   $data += $all_data;
@@ -1760,11 +1771,12 @@ function mollom_validate_analysis(&$form, &$form_state) {
 
   // Store the response returned by Mollom.
   $form_state['mollom']['response']['content'] = $result;
-  // Set form element values accordingly. Do not overwrite the entity ID with
-  // the contentId, nor a possibly existing captchaId.
+  // Set form values accordingly. Do not overwrite the entity ID.
+  // @todo Rename 'id' to 'entity_id'.
   $result['contentId'] = $result['id'];
   unset($result['id']);
   $form_state['values']['mollom'] = array_merge($form_state['values']['mollom'], $result);
+
   // #value has to be set manually to output it in case of a validation error,
   // since this is not a element-level but a form-level validation handler.
   $form['mollom']['contentId']['#value'] = $result['contentId'];
@@ -1834,15 +1846,7 @@ function mollom_validate_analysis(&$form, &$form_state) {
           $form_state['mollom']['require_moderation'] = TRUE;
         }
         else {
-          // Only throw a validation error and retrieve a CAPTCHA, if we check
-          // this post for the first time. Otherwise, mollom_validate_captcha()
-          // issued the CAPTCHA and needs to validate it prior to throwing any
-          // errors.
-          if (!$form_state['mollom']['require_captcha']) {
-            $form_state['mollom']['require_captcha'] = TRUE;
-            form_set_error('mollom][captcha', t('To complete this form, please complete the word verification below.'));
-            mollom_form_add_captcha($form['mollom'], $form_state);
-          }
+          $form_state['mollom']['require_captcha'] = TRUE;
         }
         break;
 
@@ -1869,28 +1873,22 @@ function mollom_validate_analysis(&$form, &$form_state) {
  * text analysis result is "unsure".
  */
 function mollom_validate_captcha(&$form, &$form_state) {
-  // CAPTCHA validation may only be skipped, if we do not require it in the
-  // first place, or if the user already solved a CAPTCHA correctly. We need to
-  // validate, if $form_state['mollom']['require_captcha'] is TRUE, which is
-  // either set during initialization of $form_state['mollom'] in
-  // mollom_process_form(), or after performing text analysis. The second
-  // return condition, $form_state['mollom']['passed_captcha'], may only ever be
-  // set by this validation handler and must not be changed elsewhere.
- if (!$form_state['mollom']['require_captcha'] || $form_state['mollom']['passed_captcha']) {
-    $form['mollom']['captcha']['#access'] = FALSE;
+  if (!$form_state['mollom']['require_captcha']) {
     return;
   }
 
-  // If the form is protected via text analysis and the result was "unsure",
-  // then this validation handler also runs when the CAPTCHA is initially
-  // requested by mollom_validate_analysis(), is about to be rendered, and
-  // before the user had a chance to solve it. In that case, there is no value
-  // that could be validated yet; i.e., the CAPTCHA value is empty. However, in
-  // all other cases, an empty value must be validated and sent to Mollom. The
-  // initial case has a special condition: mollom_validate_analysis() has set
-  // a form error on the CAPTCHA element asking the user to solve it in order to
-  // submit the form.
-  if ($form_state['values']['mollom']['captcha'] === '' && form_get_error($form['mollom']['captcha'])) {
+  // If there is no CAPTCHA ID yet, retrieve one and throw an error.
+  if (empty($form_state['values']['mollom']['captchaId'])) {
+    mollom_form_add_captcha($form['mollom'], $form_state);
+    form_error($form['mollom']['captcha'], t('To complete this form, please complete the word verification below.'));
+    return;
+  }
+
+  // $form_state['mollom']['passed_captcha'], may only ever be set by this
+  // validation handler and must not be changed elsewhere.
+  if ($form_state['mollom']['passed_captcha']) {
+    $form['mollom']['captcha']['#access'] = FALSE;
+    $form['mollom']['captcha']['#solved'] = TRUE;
     return;
   }
 
@@ -1904,7 +1902,7 @@ function mollom_validate_captcha(&$form, &$form_state) {
     return;
   }
   $data = array(
-    'id' => $form_state['mollom']['response']['captcha']['id'],
+    'id' => $form_state['values']['mollom']['captchaId'],
     'solution' => $form_state['values']['mollom']['captcha'],
     'authorIp' => $all_data['authorIp'],
   );
@@ -1914,7 +1912,7 @@ function mollom_validate_captcha(&$form, &$form_state) {
   if (isset($all_data['honeypot'])) {
     $data['honeypot'] = $all_data['honeypot'];
   }
-  $result = $form_state['mollom']['class']->checkCaptcha($data);
+  $result = mollom()->checkCaptcha($data);
   // Use all available data properties for log messages below.
   $data += $all_data;
 
@@ -1925,11 +1923,12 @@ function mollom_validate_captcha(&$form, &$form_state) {
 
   // Store the response for #submit handlers.
   $form_state['mollom']['response']['captcha'] = $result;
-  // Set form element values accordingly. Do not overwrite the entity ID with
-  // the contentId, nor a possibly existing captchaId.
+  // Set form values accordingly. Do not overwrite the entity ID.
+  // @todo Rename 'id' to 'entity_id'.
   $result['captchaId'] = $result['id'];
   unset($result['id']);
   $form_state['values']['mollom'] = array_merge($form_state['values']['mollom'], $result);
+
   // #value has to be set manually to output it in case of a validation error,
   // since this is not a element-level but a form-level validation handler.
   $form['mollom']['captchaId']['#value'] = $result['captchaId'];
@@ -1937,6 +1936,7 @@ function mollom_validate_captcha(&$form, &$form_state) {
   if (!empty($result['solved'])) {
     $form_state['mollom']['passed_captcha'] = TRUE;
     $form['mollom']['captcha']['#access'] = FALSE;
+    $form['mollom']['captcha']['#solved'] = TRUE;
 
     mollom_log(array(
       'message' => 'Correct CAPTCHA',
@@ -2457,10 +2457,7 @@ function mollom_get_captcha(&$form_state) {
     if (!empty($form_state['mollom']['response']['content']['id'])) {
       $data['contentId'] = $form_state['mollom']['response']['content']['id'];
     }
-    // @todo $form_state may not contain a Mollom class when being called from
-    //   mollom_captcha_js() until that gets converted to #ajax framework.
-    $mollom = (isset($form_state['mollom']['class']) ? $form_state['mollom']['class'] : mollom());
-    $result = $mollom->createCaptcha($data);
+    $result = mollom()->createCaptcha($data);
 
     // Add a log message to prevent the request log from appearing without a
     // message on CAPTCHA-only protected forms.
@@ -2470,6 +2467,7 @@ function mollom_get_captcha(&$form_state) {
 
     if (is_array($result) && isset($result['url'])) {
       $url = $result['url'];
+      $form_state['mollom']['response'][$key] = $url;
       $form_state['mollom']['response']['captcha']['id'] = $result['id'];
     }
     else {
diff --git a/tests/mollom.test b/tests/mollom.test
index fa77fda..c10115a 100644
--- a/tests/mollom.test
+++ b/tests/mollom.test
@@ -125,6 +125,9 @@ class MollomWebTestCase extends DrupalWebTestCase {
     // automatically create testing API keys.
     variable_set('mollom_testing_create_keys', $this->createKeys);
 
+    // Disable testing mode warnings.
+    variable_set('mollom_testing_mode_omit_warning', TRUE);
+
     // D7's new default theme Bartik is bogus in various locations, which leads
     // to failing tests.
     // @todo Remove this override.
@@ -914,6 +917,81 @@ class MollomWebTestCase extends DrupalWebTestCase {
 }
 
 /**
+ * Tests protection of forms.
+ */
+class MollomFormProtectionTestCase extends MollomWebTestCase {
+  protected $disableDefaultSetup = TRUE;
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Form protection',
+      'description' => 'Tests protection of forms.',
+      'group' => 'Mollom',
+    );
+  }
+
+  function setUp() {
+    parent::setUp(array('mollom', 'mollom_test'));
+    $this->setKeys();
+    $this->assertValidKeys();
+
+    // Enable excessive/aggressive page caching to resemble reverse-proxies.
+    variable_set('cache', 1);
+    // A minimum cache lifetime causes cache_clear_all() to start a session.
+    //variable_set('cache_lifetime', 60);
+    variable_set('page_cache_maximum_age', 180);
+  }
+
+  protected function setProtectionX($form_id, $mode = MOLLOM_MODE_ANALYSIS, $values = array()) {
+    if (!$mollom_form = mollom_form_load($form_id)) {
+      $mollom_form = mollom_form_new($form_id);
+    }
+    $mollom_form['mode'] = $mode;
+    if ($values) {
+      foreach ($values as $property => $value) {
+        $mollom_form[$property] = $value;
+      }
+    }
+    $status = mollom_form_save($mollom_form);
+    return $status;
+  }
+
+  /**
+   * Tests text analysis.
+   */
+  function testAnalysis() {
+    $this->setProtectionX('mollom_test_form');
+    // Prime the form + page cache.
+    $this->drupalGet('mollom-test/form');
+    $this->assertText('Views: 1');
+    $this->drupalGet('mollom-test/form');
+    $this->assertText('Views: 1');
+    $this->assertUnsureSubmit(NULL, array('title'), array(), 'Submit');
+
+    $this->drupalGet('mollom-test/form');
+    $this->assertText('Views: 1');
+    $this->assertUnsureSubmit(NULL, array('title'), array(), 'Submit');
+
+    $this->drupalGet('mollom-test/form');
+    $this->assertText('Views: 1');
+    $this->assertSpamSubmit(NULL, array('title'), array(), 'Submit');
+
+    $this->drupalGet('mollom-test/form');
+    $this->assertText('Views: 1');
+    $this->assertHamSubmit(NULL, array('title'), array(), 'Submit');
+  }
+
+  /**
+   * Tests text analysis with enabled form caching.
+   */
+  function testAnalysisFormCache() {
+    variable_set('mollom_test.form.cache', TRUE);
+    $this->testAnalysis();
+  }
+
+}
+
+/**
  * Tests testing mode functionality.
  */
 class MollomTestingModeTestCase extends MollomWebTestCase {
@@ -941,6 +1019,9 @@ class MollomTestingModeTestCase extends MollomWebTestCase {
   function setUp() {
     parent::setUp(array('mollom', 'mollom_test'));
 
+    // Enable testing mode warnings.
+    variable_del('mollom_testing_mode_omit_warning');
+
     $this->admin_user = $this->drupalCreateUser(array(
       'access administration pages',
       'administer mollom',
@@ -2956,7 +3037,7 @@ class MollomCommentFormTestCase extends MollomWebTestCase {
     // required field.
     $this->postIncorrectCaptcha(NULL, array(), t('Preview'));
     $this->assertText(t('Comment field is required.'));
-    $this->assertResponseIDInForm('captchaId', TRUE);
+    $this->assertResponseIDInForm('captchaId');
     $this->assertNoPrivacyLink();
 
     // Try to submit a correct answer for the CAPTCHA, still without required
diff --git a/tests/mollom_test.module b/tests/mollom_test.module
index 22e34ff..0f24960 100644
--- a/tests/mollom_test.module
+++ b/tests/mollom_test.module
@@ -46,6 +46,11 @@ function mollom_test_menu() {
     'page arguments' => array('mollom_test_delete_form', 2),
     'access callback' => TRUE,
   );
+  $items['mollom-test/form/views/reset'] = array(
+    'page callback' => 'mollom_test_views_reset',
+    'access callback' => TRUE,
+    'type' => MENU_CALLBACK,
+  );
   return $items;
 }
 
@@ -115,6 +120,15 @@ function mollom_test_mollom_form_info($form_id) {
 }
 
 /**
+ * Page callback; Resets the page view counter.
+ */
+function mollom_test_views_reset() {
+  variable_del('mollom_test.form.views');
+  cache_clear_all();
+  drupal_goto();
+}
+
+/**
  * Form builder for Mollom test form.
  */
 function mollom_test_form($form, &$form_state, $mid = NULL) {
@@ -137,6 +151,19 @@ function mollom_test_form($form, &$form_state, $mid = NULL) {
   // Always add an empty field the user can submit.
   $form_state['storage']['field']['new'] = '';
 
+  // Output a page view counter for page/form cache testing purposes.
+  $count = variable_get('mollom_test.form.views', 1);
+  $reset_link = l('Reset', 'mollom-test/form/views/reset', array('query' => drupal_get_destination()));
+  $form['views'] = array(
+    '#markup' => '<p>' . 'Views: ' . $count++ . ' ' . $reset_link . '</p>',
+  );
+  variable_set('mollom_test.form.views', $count);
+
+  // Conditionally enable form caching.
+  if (variable_get('mollom_test.form.cache', FALSE)) {
+    $form_state['cache'] = TRUE;
+  }
+
   $form['#tree'] = TRUE;
   $form['mid'] = array(
     '#type' => 'hidden',
diff --git a/tests/mollom_test_server.module b/tests/mollom_test_server.module
index 7135726..8c54c27 100644
--- a/tests/mollom_test_server.module
+++ b/tests/mollom_test_server.module
@@ -97,6 +97,9 @@ function mollom_test_server_rest_get_auth_header() {
  * Delivery callback for REST API endpoints.
  */
 function mollom_test_server_rest_deliver($page_callback_result) {
+  // All fake-server responses are not cached.
+  drupal_page_is_cacheable(FALSE);
+
   drupal_add_http_header('Content-Type', 'application/xml; charset=utf-8');
 
   $xml = new DOMDocument('1.0', 'utf-8');