diff --git a/lib/html.php b/lib/html.php
index 2553f3a8..ad3e6509 100644
--- a/lib/html.php
+++ b/lib/html.php
@@ -187,12 +187,18 @@ function defaultLinkTo($dom, $url)
 
     // Use long method names for compatibility with simple_html_dom and DOMDocument
 
-    foreach ($dom->getElementsByTagName('img') as $image) {
-        $image->setAttribute('src', urljoin($url, $image->getAttribute('src')));
+    $images = $dom->getElementsByTagName('img');
+    if (is_array($images)) {
+        foreach ($images as $image) {
+            $image->setAttribute('src', urljoin($url, $image->getAttribute('src')));
+        }
     }
 
-    foreach ($dom->getElementsByTagName('a') as $anchor) {
-        $anchor->setAttribute('href', urljoin($url, $anchor->getAttribute('href')));
+    $anchors = $dom->getElementsByTagName('a');
+    if (is_array($anchors)) {
+        foreach ($anchors as $anchor) {
+            $anchor->setAttribute('href', urljoin($url, $anchor->getAttribute('href')));
+        }
     }
 
     // Will never be true for DOMDocument