diff --git a/src/Admin/CommentAdmin.php b/src/Admin/CommentAdmin.php
index 6ab90f0..56b6e2b 100644
--- a/src/Admin/CommentAdmin.php
+++ b/src/Admin/CommentAdmin.php
@@ -100,7 +100,7 @@ class CommentAdmin extends LeftAndMain implements PermissionProvider
                     _t(
                         __CLASS__.'.NewComments',
                         'New ({count})',
-                        ['count' => count($newComments)]
+                        ['count' => count($newComments ?? [])]
                     ),
                     $newGrid
                 ),
@@ -109,7 +109,7 @@ class CommentAdmin extends LeftAndMain implements PermissionProvider
                     _t(
                         __CLASS__.'.ApprovedComments',
                         'Approved ({count})',
-                        ['count' => count($approvedComments)]
+                        ['count' => count($approvedComments ?? [])]
                     ),
                     $approvedGrid
                 ),
@@ -118,7 +118,7 @@ class CommentAdmin extends LeftAndMain implements PermissionProvider
                     _t(
                         __CLASS__.'.SpamComments',
                         'Spam ({count})',
-                        ['count' => count($spamComments)]
+                        ['count' => count($spamComments ?? [])]
                     ),
                     $spamGrid
                 )
diff --git a/src/Admin/CommentsGridFieldAction.php b/src/Admin/CommentsGridFieldAction.php
index dc0d867..9e143dd 100644
--- a/src/Admin/CommentsGridFieldAction.php
+++ b/src/Admin/CommentsGridFieldAction.php
@@ -19,7 +19,7 @@ class CommentsGridFieldAction implements GridField_ColumnProvider, GridField_Act
      */
     public function augmentColumns($gridField, &$columns)
     {
-        if (!in_array('Actions', $columns)) {
+        if (!in_array('Actions', $columns ?? [])) {
             $columns[] = 'Actions';
         }
     }
diff --git a/src/Admin/CommentsGridFieldApproveAction.php b/src/Admin/CommentsGridFieldApproveAction.php
index 1979109..5c175e1 100644
--- a/src/Admin/CommentsGridFieldApproveAction.php
+++ b/src/Admin/CommentsGridFieldApproveAction.php
@@ -20,7 +20,7 @@ class CommentsGridFieldApproveAction implements
      */
     public function augmentColumns($gridField, &$columns)
     {
-        if (!in_array('Actions', $columns)) {
+        if (!in_array('Actions', $columns ?? [])) {
             $columns[] = 'Actions';
         }
     }
diff --git a/src/Admin/CommentsGridFieldSpamAction.php b/src/Admin/CommentsGridFieldSpamAction.php
index cc8761c..e02c94a 100644
--- a/src/Admin/CommentsGridFieldSpamAction.php
+++ b/src/Admin/CommentsGridFieldSpamAction.php
@@ -20,7 +20,7 @@ class CommentsGridFieldSpamAction implements
      */
     public function augmentColumns($gridField, &$columns)
     {
-        if (!in_array('Actions', $columns)) {
+        if (!in_array('Actions', $columns ?? [])) {
             $columns[] = 'Actions';
         }
     }
diff --git a/src/Controllers/CommentingController.php b/src/Controllers/CommentingController.php
index 50c5fcd..a0023a5 100644
--- a/src/Controllers/CommentingController.php
+++ b/src/Controllers/CommentingController.php
@@ -115,7 +115,7 @@ class CommentingController extends Controller
      */
     public function encodeClassName($input)
     {
-        return str_replace('\\', '-', $input);
+        return str_replace('\\', '-', $input ?? '');
     }
 
     /**
@@ -126,7 +126,7 @@ class CommentingController extends Controller
      */
     public function decodeClassName($input)
     {
-        return str_replace('-', '\\', $input);
+        return str_replace('-', '\\', $input ?? '');
     }
 
     /**
diff --git a/src/Extensions/CommentsExtension.php b/src/Extensions/CommentsExtension.php
index 4e75f00..2d18c26 100644
--- a/src/Extensions/CommentsExtension.php
+++ b/src/Extensions/CommentsExtension.php
@@ -583,9 +583,9 @@ class CommentsExtension extends DataExtension
             CommentsGridFieldConfig::create()
         );
 
-        $newCount = '(' . count($newComments) . ')';
-        $approvedCount = '(' . count($approvedComments) . ')';
-        $spamCount = '(' . count($spamComments) . ')';
+        $newCount = '(' . count($newComments ?? []) . ')';
+        $approvedCount = '(' . count($approvedComments ?? []) . ')';
+        $spamCount = '(' . count($spamComments ?? []) . ')';
 
         if ($fields->hasTabSet()) {
             $tabs = TabSet::create(
diff --git a/src/Forms/CommentForm.php b/src/Forms/CommentForm.php
index c8639f5..5c046a1 100644
--- a/src/Forms/CommentForm.php
+++ b/src/Forms/CommentForm.php
@@ -145,8 +145,8 @@ class CommentForm extends Form
         }
 
         // load user data from previous form request back into form.
-        if (array_key_exists('UserData', $data)) {
-            $formData = json_decode($data['UserData'], true);
+        if (array_key_exists('UserData', $data ?? [])) {
+            $formData = json_decode($data['UserData'] ?? '', true);
 
             $this->loadDataFrom([
                 'Name' => isset($formData['Name']) ? $formData['Name'] : '',
@@ -156,7 +156,7 @@ class CommentForm extends Form
         }
 
         // allow previous value to fill if comment
-        if (array_key_exists('Comment', $data)) {
+        if (array_key_exists('Comment', $data ?? [])) {
             $prevComment = $data['Comment'];
 
             if ($prevComment && $prevComment != '') {
diff --git a/src/Model/Comment.php b/src/Model/Comment.php
index 8c47ac6..090f17b 100755
--- a/src/Model/Comment.php
+++ b/src/Model/Comment.php
@@ -608,7 +608,7 @@ class Comment extends DataObject
      */
     public function getTitle()
     {
-        $title = sprintf(_t(__CLASS__ . '.COMMENTBY', 'Comment by %s', 'Name'), $this->getAuthorName());
+        $title = sprintf(_t(__CLASS__ . '.COMMENTBY', 'Comment by %s', 'Name') ?? '', $this->getAuthorName());
 
         if ($parent = $this->Parent()) {
             if ($parent->Title) {
@@ -726,7 +726,7 @@ class Comment extends DataObject
         }
 
         // This injector cannot be set unless the 'p' element is allowed
-        if (in_array('p', $allowedElements)) {
+        if (in_array('p', $allowedElements ?? [])) {
             $config->set('AutoFormat.AutoParagraph', true);
         }
 
@@ -747,7 +747,7 @@ class Comment extends DataObject
         $use_gravatar = $this->getOption('use_gravatar');
 
         if ($use_gravatar) {
-            $gravatar = 'https://www.gravatar.com/avatar/' . md5(strtolower(trim($this->Email)));
+            $gravatar = 'https://www.gravatar.com/avatar/' . md5(strtolower(trim($this->Email ?? '')));
             $gravatarsize = $this->getOption('gravatar_size');
             $gravatardefault = $this->getOption('gravatar_default');
             $gravatarrating = $this->getOption('gravatar_rating');
diff --git a/src/Model/Comment/SecurityToken.php b/src/Model/Comment/SecurityToken.php
index e92fc76..e511ab4 100644
--- a/src/Model/Comment/SecurityToken.php
+++ b/src/Model/Comment/SecurityToken.php
@@ -37,7 +37,7 @@ class SecurityToken
      */
     protected function getToken($salt)
     {
-        return hash_pbkdf2('sha256', $this->secret, $salt, 1000, 30);
+        return hash_pbkdf2('sha256', $this->secret ?? '', $salt ?? '', 1000, 30);
     }
 
     /**
@@ -74,8 +74,8 @@ class SecurityToken
             $url,
             sprintf(
                 '?t=%s&s=%s',
-                urlencode($token),
-                urlencode($salt)
+                urlencode($token ?? ''),
+                urlencode($salt ?? '')
             )
         );
     }
@@ -113,7 +113,7 @@ class SecurityToken
         $generator = new RandomGenerator();
         $result = $generator->randomToken('sha256');
         if ($length !== null) {
-            return substr($result, 0, $length);
+            return substr($result ?? '', 0, $length);
         }
         return $result;
     }
diff --git a/tests/CommentingControllerTest.php b/tests/CommentingControllerTest.php
index ec48e37..e1e8f0d 100644
--- a/tests/CommentingControllerTest.php
+++ b/tests/CommentingControllerTest.php
@@ -179,21 +179,29 @@ class CommentingControllerTest extends FunctionalTest
         // comments sitewide
         $response = $this->get('comments/rss');
         $comment = "10 approved, non spam comments on page 1";
-        $this->assertEquals(10, substr_count($response->getBody(), "<item>"), $comment);
+        $this->assertEquals(10, substr_count($response->getBody() ?? '', "<item>"), $comment);
 
         $response = $this->get('comments/rss?start=10');
-        $this->assertEquals(4, substr_count($response->getBody(), "<item>"), "3 approved, non spam comments on page 2");
+        $this->assertEquals(
+            4,
+            substr_count($response->getBody() ?? '', "<item>"),
+            "3 approved, non spam comments on page 2"
+        );
 
         // all comments on a type
         $response = $this->get('comments/rss/SilverStripe-Comments-Tests-Stubs-CommentableItem');
-        $this->assertEquals(10, substr_count($response->getBody(), "<item>"));
+        $this->assertEquals(10, substr_count($response->getBody() ?? '', "<item>"));
 
         $response = $this->get('comments/rss/SilverStripe-Comments-Tests-Stubs-CommentableItem?start=10');
-        $this->assertEquals(4, substr_count($response->getBody(), "<item>"), "3 approved, non spam comments on page 2");
+        $this->assertEquals(
+            4,
+            substr_count($response->getBody() ?? '', "<item>"),
+            "3 approved, non spam comments on page 2"
+        );
 
         // specific page
         $response = $this->get('comments/rss/SilverStripe-Comments-Tests-Stubs-CommentableItem/'.$item->ID);
-        $this->assertEquals(1, substr_count($response->getBody(), "<item>"));
+        $this->assertEquals(1, substr_count($response->getBody() ?? '', "<item>"));
         $this->assertStringContainsString('<dc:creator>FA</dc:creator>', $response->getBody());
 
         // test accessing comments on a type that doesn't exist
diff --git a/tests/CommentsExtensionTest.php b/tests/CommentsExtensionTest.php
index dbee3cd..c07afd8 100644
--- a/tests/CommentsExtensionTest.php
+++ b/tests/CommentsExtensionTest.php
@@ -343,7 +343,7 @@ class CommentsExtensionTest extends FunctionalTest
             $results[0]->Comment
         );
 
-        $this->assertEquals(4, sizeof($results));
+        $this->assertEquals(4, sizeof($results ?? []));
     }
 
     public function testUpdateModerationFields()