diff --git a/library/Zend/Feed/Element.php b/library/Zend/Feed/Element.php
index 44b2468ef4..c4999c26b1 100644
--- a/library/Zend/Feed/Element.php
+++ b/library/Zend/Feed/Element.php
@@ -134,8 +134,8 @@ protected function ensureAppended()
     public function saveXml()
     {
         // Return a complete document including XML prologue.
-        $doc = new DOMDocument($this->_element->ownerDocument->version,
-                               $this->_element->ownerDocument->actualEncoding);
+        $doc = new DOMDocument((string) $this->_element->ownerDocument->version,
+                               (string) $this->_element->ownerDocument->actualEncoding);
         $doc->appendChild($doc->importNode($this->_element, true));
         return $doc->saveXML();
     }
diff --git a/library/Zend/Feed/Pubsubhubbub/Model/Subscription.php b/library/Zend/Feed/Pubsubhubbub/Model/Subscription.php
index 74c59798d5..ba4233ecf1 100644
--- a/library/Zend/Feed/Pubsubhubbub/Model/Subscription.php
+++ b/library/Zend/Feed/Pubsubhubbub/Model/Subscription.php
@@ -114,7 +114,7 @@ public function hasSubscription($key)
                 .' of "' . $key . '" must be a non-empty string');
         }
         $result = $this->_db->find($key);
-        if (count($result)) {
+        if (count($result ?? [])) {
             return true;
         }
         return false;
diff --git a/library/Zend/Feed/Reader/Entry/Rss.php b/library/Zend/Feed/Reader/Entry/Rss.php
index 57c00a141b..90c4161b10 100644
--- a/library/Zend/Feed/Reader/Entry/Rss.php
+++ b/library/Zend/Feed/Reader/Entry/Rss.php
@@ -193,7 +193,7 @@ public function getAuthors()
             }
         }
 
-        if (count($authors) === 0) {
+        if (count($authors ?? []) === 0) {
             $authors = $this->getExtension('Atom')->getAuthors();
         } else {
             $authors = new Zend_Feed_Reader_Collection_Author(
@@ -201,7 +201,7 @@ public function getAuthors()
             );
         }
 
-        if (count($authors) === 0) {
+        if (count($authors ?? []) === 0) {
             $authors = null;
         }
 
diff --git a/library/Zend/Feed/Reader/Extension/Atom/Entry.php b/library/Zend/Feed/Reader/Extension/Atom/Entry.php
index 6001320051..d1c5429ff2 100644
--- a/library/Zend/Feed/Reader/Extension/Atom/Entry.php
+++ b/library/Zend/Feed/Reader/Extension/Atom/Entry.php
@@ -163,7 +163,7 @@ public function getContent()
             $content = $this->getDescription();
         }
 
-        $this->_data['content'] = trim($content);
+        $this->_data['content'] = trim((string) $content);
 
         return $this->_data['content'];
     }
diff --git a/library/Zend/Feed/Reader/Feed/Rss.php b/library/Zend/Feed/Reader/Feed/Rss.php
index 7f87343525..e339817e9f 100644
--- a/library/Zend/Feed/Reader/Feed/Rss.php
+++ b/library/Zend/Feed/Reader/Feed/Rss.php
@@ -143,7 +143,7 @@ public function getAuthors()
             }
         }
 
-        if (count($authors) === 0) {
+        if (count($authors ?? []) === 0) {
             $authors = $this->getExtension('Atom')->getAuthors();
         } else {
             $authors = new Zend_Feed_Reader_Collection_Author(
@@ -151,7 +151,7 @@ public function getAuthors()
             );
         }
 
-        if (count($authors) === 0) {
+        if (count($authors ?? []) === 0) {
             $authors = null;
         }