diff --git a/forms/Form.php b/forms/Form.php
index 537b36fd52e..edd3181763e 100644
--- a/forms/Form.php
+++ b/forms/Form.php
@@ -277,10 +277,20 @@ public function httpSubmission($request) {
 	
 		// Protection against CSRF attacks
 		$token = $this->getSecurityToken();
-		if(!$token->checkRequest($request)) {
-			$this->httpError(400, _t("Form.CSRF_FAILED_MESSAGE",
-				"There seems to have been a technical problem. Please click the back button,"
-				. " refresh your browser, and try again."));
+		if( ! $token->checkRequest($request)) {
+			if (empty($vars['SecurityID'])) {
+				$this->httpError(400, _t("Form.CSRF_FAILED_MESSAGE",
+					"There seems to have been a technical problem. Please click the back button, 
+					refresh your browser, and try again."));
+			} else {
+				Session::set("FormInfo.{$this->FormName()}.data", $this->getData());
+				Session::set("FormInfo.{$this->FormName()}.errors", array());
+				$this->sessionMessage(
+					_t("Form.CSRF_EXPIRED_MESSAGE", "Your session has expired. Please re-submit the form."),
+					"warning"
+				);
+				return $this->controller->redirectBack();
+			}
 		}
 		
 		// Determine the action button clicked
diff --git a/tests/forms/FormTest.php b/tests/forms/FormTest.php
index 0a7fb807cbf..5ac98719ec1 100644
--- a/tests/forms/FormTest.php
+++ b/tests/forms/FormTest.php
@@ -311,7 +311,22 @@ public function testDisableSecurityTokenAcceptsSubmissionWithoutToken() {
 			)
 		);
 		$this->assertEquals(400, $response->getStatusCode(), 'Submission fails without security token');
-		
+
+		$response = $this->get('FormTest_ControllerWithSecurityToken');
+		$response = $this->post(
+			'FormTest_ControllerWithSecurityToken/Form',
+			array(
+				'Email' => 'test@test.com',
+				'action_doSubmit' => 1,
+				'SecurityID' => -1
+			)
+		);
+		$this->assertEquals(200, $response->getStatusCode(), 'Submission reloads form if security token invalid');
+
+		$matched = $this->cssParser()->getBySelector('#Form_Form_Email');
+		$attrs = $matched[0]->attributes();
+		$this->assertEquals('test@test.com', (string)$attrs['value'], 'Submitted data is preserved');
+
 		$response = $this->get('FormTest_ControllerWithSecurityToken');
 		$tokenEls = $this->cssParser()->getBySelector('#Form_Form_SecurityID');
 		$this->assertEquals(