diff --git a/src/IFramePage.php b/src/IFramePage.php
index bd11733..2715c52 100644
--- a/src/IFramePage.php
+++ b/src/IFramePage.php
@@ -142,8 +142,8 @@ class IFramePage extends Page
 
         //whitelist allowed URL schemes
         $allowed_schemes = array('http', 'https');
-        if ($matches = parse_url($this->IFrameURL)) {
-            if (isset($matches['scheme']) && !in_array($matches['scheme'], $allowed_schemes)) {
+        if ($matches = parse_url($this->IFrameURL ?? '')) {
+            if (isset($matches['scheme']) && !in_array($matches['scheme'], $allowed_schemes ?? [])) {
                 $result->addError(_t(__CLASS__ . '.VALIDATION_BANNEDURLSCHEME', "This URL scheme is not allowed."));
             }
         }
diff --git a/src/IFramePageController.php b/src/IFramePageController.php
index 2050a1e..6a5ea22 100644
--- a/src/IFramePageController.php
+++ b/src/IFramePageController.php
@@ -16,8 +16,8 @@ class IFramePageController extends PageController
         if ($desiredProtocol && $currentProtocol !== $desiredProtocol) {
             $enforcedLocation = preg_replace(
                 "#^${currentProtocol}#",
-                $desiredProtocol,
-                $this->AbsoluteLink()
+                $desiredProtocol ?? '',
+                $this->AbsoluteLink() ?? ''
             );
             return $this->redirect($enforcedLocation);
         }