diff --git a/src/Forms/GridField/GridFieldAddByDBField.php b/src/Forms/GridField/GridFieldAddByDBField.php
index ff5509e3..95613057 100644
--- a/src/Forms/GridField/GridFieldAddByDBField.php
+++ b/src/Forms/GridField/GridFieldAddByDBField.php
@@ -234,6 +234,6 @@ public function getHTMLFragments($gridField)
         $forTemplate->Fields->push($textField);
         $forTemplate->Fields->push($addAction);
 
-        return [$this->targetFragment => $forTemplate->renderWith(self::class)];
+        return [$this->targetFragment => $forTemplate->renderWith(GridFieldAddByDBField::class)];
     }
 }
diff --git a/src/Model/Blog.php b/src/Model/Blog.php
index d3aeec91..c843997f 100644
--- a/src/Model/Blog.php
+++ b/src/Model/Blog.php
@@ -475,7 +475,7 @@ public function canEditEditors($member = null)
             return $extended;
         }
 
-        return Permission::checkMember($member, self::MANAGE_USERS);
+        return Permission::checkMember($member, Blog::MANAGE_USERS);
     }
 
     /**
@@ -499,7 +499,7 @@ public function canEditWriters($member = null)
             return true;
         }
 
-        return Permission::checkMember($member, self::MANAGE_USERS);
+        return Permission::checkMember($member, Blog::MANAGE_USERS);
     }
 
     /**
@@ -523,7 +523,7 @@ public function canEditContributors($member = null)
             return true;
         }
 
-        return Permission::checkMember($member, self::MANAGE_USERS);
+        return Permission::checkMember($member, Blog::MANAGE_USERS);
     }
 
     /**
diff --git a/src/Model/BlogObject.php b/src/Model/BlogObject.php
index 677a9742..e5760e09 100644
--- a/src/Model/BlogObject.php
+++ b/src/Model/BlogObject.php
@@ -69,7 +69,7 @@ public function validate()
         }
 
         if ($this->getDuplicatesByField('Title')->count() > 0) {
-            $validation->addError($this->getDuplicateError(), self::DUPLICATE_EXCEPTION);
+            $validation->addError($this->getDuplicateError(), BlogObject::DUPLICATE_EXCEPTION);
         }
 
         return $validation;
@@ -204,7 +204,7 @@ public function generateURLSegment($increment = 0)
      */
     protected function getDuplicatesByField($field)
     {
-        $duplicates = DataList::create(self::class)
+        $duplicates = DataList::create(BlogObject::class)
             ->filter(
                 [
                     $field   => $this->$field,
diff --git a/tests/php/Widgets/BlogArchiveWidgetTest.php b/tests/php/Widgets/BlogArchiveWidgetTest.php
index 6e4f7939..071dfda3 100644
--- a/tests/php/Widgets/BlogArchiveWidgetTest.php
+++ b/tests/php/Widgets/BlogArchiveWidgetTest.php
@@ -18,7 +18,7 @@ class BlogArchiveWidgetTest extends SapphireTest
     protected function setUp(): void
     {
         if (!class_exists(Widget::class)) {
-            self::$fixture_file = null;
+            BlogArchiveWidgetTest::$fixture_file = null;
             parent::setUp();
             $this->markTestSkipped('Test requires silverstripe/widgets to be installed.');
         }