diff --git a/mollom.module b/mollom.module
index 05eb729..1ff9f8f 100644
--- a/mollom.module
+++ b/mollom.module
@@ -1405,52 +1405,68 @@ function _mollom_status($reset = FALSE) {
   $private_key = $mollom->loadConfiguration('privateKey');
   $status['keys'] = (!empty($public_key) && !empty($private_key));
 
-  // If we have keys and are asked to reset, check whether keys are valid.
-  if ($status['keys'] && $reset) {
-    $status['keys valid'] = $mollom->verifyKeys();
-    if ($status['keys valid'] === TRUE) {
-      mollom_log(array(
-        'message' => 'API keys are valid.',
-      ), WATCHDOG_INFO);
-    }
-    elseif ($status['keys valid'] === Mollom::REQUEST_ERROR) {
-      mollom_log(array(
-        'message' => 'Invalid client configuration.',
-      ), WATCHDOG_ERROR);
-    }
-    elseif ($status['keys valid'] === Mollom::AUTH_ERROR) {
-      mollom_log(array(
-        'message' => 'Invalid API keys.',
-      ), WATCHDOG_ERROR);
-    }
-    // If the response is neither positive nor a known negative error, and
-    // the previous status was positive, then the Mollom service might be
-    // temporarily down. In this case, return an enforced RESPONSE_ERROR to
-    // indicate a server-side service failure, but do not update the stored
-    // status.
-    // @todo Test this.
-    elseif ($current_status['keys valid'] === TRUE) {
-      $status['keys valid'] = Mollom::RESPONSE_ERROR;
-      // Do not update the stored configuration status with the bogus result
-      // caused by the server-side failure.
-      $reset = FALSE;
-      mollom_log(array(
-        'message' => 'API keys could not be verified.',
-      ), WATCHDOG_WARNING);
-    }
-  }
-  // Otherwise, if there are no keys, they cannot be valid.
-  elseif (!$status['keys']) {
+  // If there are no keys, then they cannot be valid.
+  if (!$status['keys']) {
     $status['keys valid'] = FALSE;
   }
 
-  // Update stored status upon reset, but only if the status changed, as a
-  // variable_set() invalidates the variable cache.
-  // Requires array_diff_assoc() instead of ($current_status != $status), since
-  // 'keys valid' may be an error code integer, which is equal to TRUE, so a
-  // type-agnostic strict comparison is required.
-  if ($reset && array_diff_assoc($current_status, $status)) {
-    variable_set('mollom_status', $status);
+  // If we have keys and are asked to reset, check whether keys are valid.
+  if ($status['keys'] && $reset) {
+    if (!lock_acquire('mollom_status', 5)) {
+      lock_wait('mollom_status');
+      // variable_initialize() cannot be safely called again, so retrieve the
+      // value directly from the database.
+      $db_status = db_query('SELECT value FROM {variable} WHERE name = :name', array(
+        ':name' => 'mollom_status',
+      ))->fetchField();
+      if ($db_status) {
+        $status = unserialize($db_status);
+      }
+    }
+    else {
+      $status['keys valid'] = $mollom->verifyKeys();
+      if ($status['keys valid'] === TRUE) {
+        mollom_log(array(
+          'message' => 'API keys are valid.',
+        ), WATCHDOG_INFO);
+      }
+      elseif ($status['keys valid'] === Mollom::REQUEST_ERROR) {
+        mollom_log(array(
+          'message' => 'Invalid client configuration.',
+        ), WATCHDOG_ERROR);
+      }
+      elseif ($status['keys valid'] === Mollom::AUTH_ERROR) {
+        mollom_log(array(
+          'message' => 'Invalid API keys.',
+        ), WATCHDOG_ERROR);
+      }
+      // If the response is neither positive nor a known negative error, and
+      // the previous status was positive, then the Mollom service might be
+      // temporarily down. In this case, return an enforced RESPONSE_ERROR to
+      // indicate a server-side service failure, but do not update the stored
+      // status.
+      // @todo Test this.
+      elseif ($current_status['keys valid'] === TRUE) {
+        $status['keys valid'] = Mollom::RESPONSE_ERROR;
+        // Do not update the stored configuration status with the bogus result
+        // caused by the server-side failure.
+        $reset = FALSE;
+        mollom_log(array(
+          'message' => 'API keys could not be verified.',
+        ), WATCHDOG_WARNING);
+      }
+
+      // Update stored status upon reset, but only if the status changed, as a
+      // variable_set() invalidates the variable cache.
+      // Requires array_diff_assoc() instead of ($current_status != $status),
+      // since 'keys valid' may be an error code integer (equaling TRUE), so a
+      // strict comparison is required.
+      if (array_diff_assoc($current_status, $status)) {
+        variable_set('mollom_status', $status);
+      }
+
+      lock_release('mollom_status');
+    }
   }
 
   return ($status['keys valid'] === TRUE ? TRUE : $status);