diff --git a/MultisiteLanguageSwitcher.php b/MultisiteLanguageSwitcher.php
index f5775da5..5e992ea2 100644
--- a/MultisiteLanguageSwitcher.php
+++ b/MultisiteLanguageSwitcher.php
@@ -31,6 +31,10 @@
  * @package msls
  */
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 if ( file_exists( __DIR__ . '/vendor/autoload.php' ) ) {
 	require __DIR__ . '/vendor/autoload.php';
 }
diff --git a/includes/ContentImport/ContentImporter.php b/includes/ContentImport/ContentImporter.php
index d9241cf7..761ba89f 100644
--- a/includes/ContentImport/ContentImporter.php
+++ b/includes/ContentImport/ContentImporter.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls\ContentImport;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\ContentImport\Importers\Importer;
 use lloc\Msls\ContentImport\Importers\Map;
 use lloc\Msls\ContentImport\Importers\WithRequestPostAttributes;
diff --git a/includes/ContentImport/Service.php b/includes/ContentImport/Service.php
index ac58828e..c0c99618 100644
--- a/includes/ContentImport/Service.php
+++ b/includes/ContentImport/Service.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls\ContentImport;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\ContentImport\LogWriters\AdminNoticeLogger;
 use lloc\Msls\MslsRegistryInstance;
 
diff --git a/includes/MslsAdmin.php b/includes/MslsAdmin.php
index 5120dfd0..6b462741 100644
--- a/includes/MslsAdmin.php
+++ b/includes/MslsAdmin.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\Component\Input\Checkbox;
 use lloc\Msls\Component\Input\Group;
 use lloc\Msls\Component\Input\Label;
diff --git a/includes/MslsAdminBar.php b/includes/MslsAdminBar.php
index 2251b089..c0fb5fc1 100644
--- a/includes/MslsAdminBar.php
+++ b/includes/MslsAdminBar.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 class MslsAdminBar {
 
 	/**
diff --git a/includes/MslsBlogCollection.php b/includes/MslsBlogCollection.php
index 5cdf86ad..188c8853 100644
--- a/includes/MslsBlogCollection.php
+++ b/includes/MslsBlogCollection.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 /**
  * Collection of blog-objects
  *
diff --git a/includes/MslsContentFilter.php b/includes/MslsContentFilter.php
index 94742bae..313be0da 100644
--- a/includes/MslsContentFilter.php
+++ b/includes/MslsContentFilter.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 class MslsContentFilter {
 
 	/**
diff --git a/includes/MslsCustomColumn.php b/includes/MslsCustomColumn.php
index 9c968a2f..849f98b1 100644
--- a/includes/MslsCustomColumn.php
+++ b/includes/MslsCustomColumn.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\Component\Component;
 
 /**
diff --git a/includes/MslsCustomColumnTaxonomy.php b/includes/MslsCustomColumnTaxonomy.php
index 03f2b011..9bae247f 100644
--- a/includes/MslsCustomColumnTaxonomy.php
+++ b/includes/MslsCustomColumnTaxonomy.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 /**
  * Handling of existing/not existing translations in the backend
  * listings of various taxonomies
diff --git a/includes/MslsCustomFilter.php b/includes/MslsCustomFilter.php
index 791ef424..9af74526 100644
--- a/includes/MslsCustomFilter.php
+++ b/includes/MslsCustomFilter.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\Component\Input\Select;
 use lloc\Msls\Query\TranslatedPostIdQuery;
 
diff --git a/includes/MslsMetaBox.php b/includes/MslsMetaBox.php
index f83fcca4..3430774c 100644
--- a/includes/MslsMetaBox.php
+++ b/includes/MslsMetaBox.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\Component\Component;
 use lloc\Msls\Component\Wrapper;
 use lloc\Msls\ContentImport\MetaBox as ContentImportMetaBox;
diff --git a/includes/MslsOptions.php b/includes/MslsOptions.php
index b5c9526a..e17339e1 100644
--- a/includes/MslsOptions.php
+++ b/includes/MslsOptions.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\Component\Icon\IconPng;
 
 /**
diff --git a/includes/MslsOptionsTaxTerm.php b/includes/MslsOptionsTaxTerm.php
index 1d1bc110..9147748b 100644
--- a/includes/MslsOptionsTaxTerm.php
+++ b/includes/MslsOptionsTaxTerm.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 /**
  * MslsOptionsTaxTerm
  *
diff --git a/includes/MslsPlugin.php b/includes/MslsPlugin.php
index 7f6506cb..670ca639 100644
--- a/includes/MslsPlugin.php
+++ b/includes/MslsPlugin.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\Query\BlogsInNetworkQuery;
 use lloc\Msls\Query\CleanupOptionsQuery;
 
diff --git a/includes/MslsPostTag.php b/includes/MslsPostTag.php
index d3c313df..2a825c63 100644
--- a/includes/MslsPostTag.php
+++ b/includes/MslsPostTag.php
@@ -2,6 +2,10 @@
 
 namespace lloc\Msls;
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 use lloc\Msls\Component\Component;
 
 /**
diff --git a/includes/deprectated.php b/includes/deprectated.php
index 60fb5f3d..8af510c6 100644
--- a/includes/deprectated.php
+++ b/includes/deprectated.php
@@ -2,6 +2,10 @@
 
 declare(strict_types=1);
 
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
 /**
  * Deprecated: Get the output for using the links to the translations in your code.
  *
diff --git a/src/msls-widget-block/render.php b/src/msls-widget-block/render.php
index 77f974a4..fd0554ce 100644
--- a/src/msls-widget-block/render.php
+++ b/src/msls-widget-block/render.php
@@ -1,3 +1,5 @@
-<?php
+<?php if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
 
 msls_the_switcher();