diff --git a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc
index 011e250b7f..e1142d9b3c 100644
--- a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc
+++ b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.1.inc
@@ -683,4 +683,16 @@ class Acronym_AsymmetricVisibilityProperties {
     public function __construct(public protected(set) int $foo = 0) {} // Ok.
 }
 
+/*
+ * Safeguard correct handling of all types of namespaced function calls.
+ */
+\define('SOME_GLOBAL', [ 1, 2, 3 ]); // Bad.
+MyNamespace\define('SOME_GLOBAL', [ 1, 2, 3 ]); // Ok.
+\MyNamespace\define('SOME_GLOBAL', [ 1, 2, 3 ]); // Ok.
+namespace\define('SOME_GLOBAL', [ 1, 2, 3 ]); // Ok. The sniff should start flagging this once it can resolve relative namespaces.
+\do_action( 'plugin_action' ); // Bad.
+MyNamespace\do_action( 'plugin_action' ); // Ok.
+\MyNamespace\do_action( 'plugin_action' ); // Ok.
+namespace\do_action( 'plugin_action' ); // Ok. The sniff should start flagging this once it can resolve relative namespaces.
+
 // phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[]
diff --git a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.3.inc b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.3.inc
index be1eb3627f..a909f6bd83 100644
--- a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.3.inc
+++ b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.3.inc
@@ -21,4 +21,35 @@ $acronym_test = new class extends \PHPUnit_Framework_TestCase {
 	}
 };
 
+/*
+ * Safeguard correct handling of namespaced extending classes.
+ */
+class Some_Test extends PHPUnit_Framework_TestCase {
+
+    public function testPass() {
+        do_action( 'some-action', $something );
+    }
+}
+
+class Some_Test extends MyNamespace\PHPUnit_Framework_TestCase {
+
+    public function testPass() {
+        do_action( 'some-action', $something );
+    }
+}
+
+class Some_Test extends \MyNamespace\PHPUnit_Framework_TestCase {
+
+    public function testPass() {
+        do_action( 'some-action', $something );
+    }
+}
+
+class Some_Test extends namespace\PHPUnit_Framework_TestCase {
+
+    public function testPass() {
+        do_action( 'some-action', $something );
+    }
+}
+
 // phpcs:set WordPress.NamingConventions.PrefixAllGlobals prefixes[]
diff --git a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.php b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.php
index b9beb09ff6..aafe4da8b2 100644
--- a/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.php
+++ b/WordPress/Tests/NamingConventions/PrefixAllGlobalsUnitTest.php
@@ -96,6 +96,8 @@ public function getErrorList( $testFile = 'PrefixAllGlobalsUnitTest.1.inc' ) {
 					616 => 1,
 					617 => 1,
 					633 => 1,
+					689 => 1,
+					693 => 1,
 				);
 
 			case 'PrefixAllGlobalsUnitTest.4.inc':
@@ -104,10 +106,17 @@ public function getErrorList( $testFile = 'PrefixAllGlobalsUnitTest.1.inc' ) {
 					18 => 1,
 				);
 
+			case 'PrefixAllGlobalsUnitTest.3.inc':
+				// Test class - non-prefixed constant is fine.
+				return array(
+					30 => 1,
+					37 => 1,
+					44 => 1,
+					51 => 1,
+				);
+
 			case 'PrefixAllGlobalsUnitTest.2.inc':
 				// Namespaced - all OK, fall through to the default case.
-			case 'PrefixAllGlobalsUnitTest.3.inc':
-				// Test class - non-prefixed constant is fine, fall through to the default case.
 			default:
 				return array();
 		}
diff --git a/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.1.inc b/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.1.inc
index 830c3552d6..c983dbcc8e 100644
--- a/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.1.inc
+++ b/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.1.inc
@@ -121,3 +121,14 @@ do_action( 'admin_head_' .  $fn( 'UPPERCASE', 'wrong-delimiter' ) . '_action' );
 do_action_ref_array( hook: 'My-Hook', args: $args ); // OK. Well, not really, but using the wrong parameter name, so not our concern.
 do_action_ref_array( args: $args, hook_name: 'my_hook', ); // OK.
 do_action_ref_array( args: $args, hook_name: 'My-Hook', ); // Error - use lowercase + warning about dash.
+
+/*
+ * Safeguard correct handling of all types of namespaced function calls.
+ */
+\apply_filters( 'adminHead', $variable ); // Error.
+MyNamespace\apply_filters( 'adminHead', $variable ); // Ok.
+\MyNamespace\apply_filters( 'adminHead', $variable ); // Ok.
+namespace\apply_filters( 'adminHead', $variable ); // Ok. The sniff should start flagging this once it can resolve relative namespaces.
+do_action( 'admin_head_' .  MyNamespace\my_function('UPPERCASE') . '_action' ); // Ok.
+do_action( 'admin_head_' .  \MyNamespace\my_function('UPPERCASE') . '_action' ); // Ok.
+do_action( 'admin_head_' .  namespace\my_function('UPPERCASE') . '_action' ); // Ok.
diff --git a/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.php b/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.php
index aac97da195..98649fb620 100644
--- a/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.php
+++ b/WordPress/Tests/NamingConventions/ValidHookNameUnitTest.php
@@ -75,6 +75,7 @@ public function getErrorList( $testFile = 'ValidHookNameUnitTest.1.inc' ) {
 					114 => 1,
 					115 => 1,
 					123 => 1,
+					128 => 1,
 				);
 
 			case 'ValidHookNameUnitTest.2.inc':
diff --git a/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.inc b/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.inc
index f007d150bd..45f7bef881 100644
--- a/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.inc
+++ b/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.inc
@@ -84,3 +84,11 @@ $decoded = @hex2bin( $data );
 // phpcs:set WordPress.PHP.NoSilencedErrors context_length 0
 echo @some_userland_function( $param ); // Bad.
 // phpcs:set WordPress.PHP.NoSilencedErrors context_length 6
+
+/*
+ * Safeguard correct handling of namespaced function calls (fully qualified is already tested above).
+ */
+$file = @MyNS\MyClass::file_get_contents( $file ); // Bad.
+$file = @MyNS\MyClass\file_get_contents( $file ); // Bad.
+$file = @namespace\MyNS\MyClass::file_get_contents( $file ); // Bad.
+$file = @namespace\file_get_contents( $file ); // The sniff should stop flagging this once it can resolve relative namespaces.
diff --git a/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.php b/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.php
index 7a576b992c..038c2c8d71 100644
--- a/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.php
+++ b/WordPress/Tests/PHP/NoSilencedErrorsUnitTest.php
@@ -61,6 +61,10 @@ public function getWarningList() {
 			71 => 1,
 			78 => 1,
 			85 => 1,
+			91 => 1,
+			92 => 1,
+			93 => 1,
+			94 => 1,
 		);
 	}
 }
diff --git a/WordPress/Tests/Security/NonceVerificationUnitTest.1.inc b/WordPress/Tests/Security/NonceVerificationUnitTest.1.inc
index aee51ae39a..9e01f33a92 100644
--- a/WordPress/Tests/Security/NonceVerificationUnitTest.1.inc
+++ b/WordPress/Tests/Security/NonceVerificationUnitTest.1.inc
@@ -524,3 +524,88 @@ function different_function_name() {
     update_post_meta( (int) $_POST['id'], 'a_key', $_POST['a_value'] );
 }
 // phpcs:set WordPress.Security.NonceVerification customNonceVerificationFunctions[]
+
+function test_fully_qualified_call_to_global_nonce_verification_function() {
+    if ( ! is_numeric ( $_POST['foo'] ) ) {
+        return;
+    }
+
+    \wp_verify_nonce( 'some_action' ); // OK.
+}
+
+function test_namespaced_calls_to_incorrect_functions() {
+    if ( ! is_numeric ( $_POST['foo'] ) ) {
+        return;
+    }
+
+    MyNamespace\wp_verify_nonce( 'some_action' ); // Bad.
+    \MyNamespace\wp_verify_nonce( 'some_action' ); // Bad.
+    namespace\wp_verify_nonce( 'some_action' ); // Bad, but should become ok once the sniff is able to resolve relative namespaces.
+}
+
+function allow_fully_qualified_key_exists_functions() {
+    if ( \array_key_exists('foo', $_POST) === false ) { // OK.
+        return;
+    }
+
+    wp_verify_nonce( 'some_action' );
+}
+
+function disallow_namespaced_key_exists_functions() {
+    if ( MyNamespace\array_key_exists( 'foo', $_POST ) === false // Bad.
+        || \MyNamespace\array_key_exists( 'foo', $_POST ) === false // Bad.
+        || namespace\array_key_exists( 'foo', $_POST ) === false // Bad, but should become ok once the sniff is able to resolve relative namespaces.
+    ) {
+        return;
+    }
+
+    wp_verify_nonce( 'some_action' );
+}
+
+function allow_fully_qualified_type_test_functions() {
+    if ( ! \is_numeric ( $_POST['foo'] ) ) { // OK.
+        return;
+    }
+
+    \wp_verify_nonce( 'some_action' ); // OK.
+}
+
+function disallow_namespaced_type_test_functions() {
+    if ( ! MyNamespace\is_numeric( $_POST['foo'] ) // Bad.
+        || ! MyNamespace\is_numeric( $_POST['foo'] ) // Bad.
+        || ! namespace\is_numeric( $_POST['foo'] ) ) // Bad, but should become ok once the sniff is able to resolve relative namespaces.
+    {
+        return;
+    }
+
+    \wp_verify_nonce( 'some_action' ); // OK.
+}
+
+function allow_fully_qualified_array_comparison_functions() {
+    if ( \in_array( $_GET['action'], $valid_actions, true ) ) { // OK.
+        check_admin_referer( 'foo' );
+    }
+}
+
+function disallow_namespaced_array_comparison_functions() {
+    if ( MyNamespace\in_array( $_GET['action'], $valid_actions, true ) // Bad.
+        || \MyNamespace\in_array( $_GET['action'], $valid_actions, true ) // Bad.
+        || namespace\in_array( $_GET['action'], $valid_actions, true ) // Bad, but should become ok once the sniff is able to resolve relative namespaces.
+    ) {
+        check_admin_referer( 'foo' );
+    }
+}
+
+function allow_fully_qualified_unslashing_functions() {
+    $var = \stripslashes_from_strings_only( $_POST['foo'] ); // OK.
+    wp_verify_nonce( $var );
+    echo $var;
+}
+
+function disallow_namespaced_unslashing_functions() {
+    $var = MyNamespace\stripslashes_from_strings_only( $_POST['foo'] ); // Bad.
+    $var = \MyNamespace\stripslashes_from_strings_only( $_POST['foo'] ); // Bad.
+    $var = namespace\stripslashes_from_strings_only( $_POST['foo'] ); // Bad, but should become ok once the sniff is able to resolve relative namespaces.
+    wp_verify_nonce( $var );
+    echo $var;
+}
diff --git a/WordPress/Tests/Security/NonceVerificationUnitTest.php b/WordPress/Tests/Security/NonceVerificationUnitTest.php
index aa5e832e83..1a74732b32 100644
--- a/WordPress/Tests/Security/NonceVerificationUnitTest.php
+++ b/WordPress/Tests/Security/NonceVerificationUnitTest.php
@@ -75,6 +75,16 @@ public function getErrorList( $testFile = '' ) {
 					470 => 1,
 					478 => 1,
 					524 => 2,
+					537 => 1,
+					555 => 1,
+					556 => 1,
+					557 => 1,
+					574 => 1,
+					575 => 1,
+					576 => 1,
+					606 => 1,
+					607 => 1,
+					608 => 1,
 				);
 
 			case 'NonceVerificationUnitTest.2.inc':
@@ -107,6 +117,9 @@ public function getWarningList( $testFile = '' ) {
 				return array(
 					365 => 1,
 					379 => 1,
+					591 => 1,
+					592 => 1,
+					593 => 1,
 				);
 
 			case 'NonceVerificationUnitTest.4.inc':
diff --git a/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc b/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc
index d33d0a18e0..fb5e1b8526 100644
--- a/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc
+++ b/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc
@@ -281,5 +281,13 @@ __ (
     $args
 );
 
+/*
+ * Safeguard correct handling of namespaced function calls (partially qualified is already tested above).
+ */
+\MyNamespace\load_textdomain( 'text-domain', '/path/to/file.mo' );
+namespace\load_textdomain( 'text-domain', '/path/to/file.mo' );
+\load_textdomain( 'text-domain', '/path/to/file.mo' );
+\load_textdomain();
+
 // phpcs:set WordPress.Utils.I18nTextDomainFixer old_text_domain[]
 // phpcs:set WordPress.Utils.I18nTextDomainFixer new_text_domain false
diff --git a/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc.fixed b/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc.fixed
index f7fd2c6f4e..f47da4e173 100644
--- a/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc.fixed
+++ b/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.4.inc.fixed
@@ -287,5 +287,13 @@ __ (
     'something-else'
 );
 
+/*
+ * Safeguard correct handling of namespaced function calls (partially qualified is already tested above).
+ */
+\MyNamespace\load_textdomain( 'text-domain', '/path/to/file.mo' );
+namespace\load_textdomain( 'text-domain', '/path/to/file.mo' );
+\load_textdomain( 'something-else', '/path/to/file.mo' );
+\load_textdomain( 'something-else' );
+
 // phpcs:set WordPress.Utils.I18nTextDomainFixer old_text_domain[]
 // phpcs:set WordPress.Utils.I18nTextDomainFixer new_text_domain false
diff --git a/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.php b/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.php
index a8c7c95e84..872050aa97 100644
--- a/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.php
+++ b/WordPress/Tests/Utils/I18nTextDomainFixerUnitTest.php
@@ -154,6 +154,8 @@ public function getErrorList( $testFile = '' ) {
 					245 => 1,
 					277 => 1,
 					278 => 1,
+					289 => 1,
+					290 => 1,
 				);
 
 			default:
diff --git a/WordPress/Tests/WP/CronIntervalUnitTest.inc b/WordPress/Tests/WP/CronIntervalUnitTest.inc
index e9541f49d2..a2623c4956 100644
--- a/WordPress/Tests/WP/CronIntervalUnitTest.inc
+++ b/WordPress/Tests/WP/CronIntervalUnitTest.inc
@@ -165,7 +165,7 @@ add_filter( 'cron_schedules', function ( $schedules ) {
 class FQNConstants {
 	public function add_schedules() {
 		add_filter( 'cron_schedules', array( $this, 'add_weekly_schedule' ) ); // Ok: > 15 min.
-		add_filter( 'cron_schedules', array( $this, 'add_eight_minute_schedule' ) ); // Warning: 8 min.
+		\add_filter( 'cron_schedules', array( $this, 'add_eight_minute_schedule' ) ); // Warning: 8 min.
 		add_filter( 'cron_schedules', array( $this, 'add_hundred_minute_schedule' ) ); // Warning: time undetermined.
 		add_filter( 'cron_schedules', array( $this, 'sneaky_fake_wp_constant_schedule' ) ); // Warning: time undetermined.
 	}
@@ -326,3 +326,12 @@ function first_class_six_min_schedule( $schedules ) {
 }
 add_filter( 'cron_schedules', first_class_six_min_schedule(...)); // Warning: 6 min.
 add_filter( 'cron_schedules', 'first_class_six_min_schedule'(...)); // Warning: 6 min.
+add_filter( 'cron_schedules', \first_class_six_min_schedule(...)); // Warning: 6 min.
+
+/*
+ * Safeguard correct handling of all types of namespaced function calls (except FQN global function call which is
+ * handled above).
+ */
+MyNamespace\add_filter( 'cron_schedules', 'unknown_callback' ); // Ok.
+\MyNamespace\add_filter( 'cron_schedules', 'unknown_callback' ); // Ok.
+namespace\add_filter( 'cron_schedules', 'unknown_callback' ); // Ok. The sniff should start flagging this once it can resolve relative namespaces.
diff --git a/WordPress/Tests/WP/CronIntervalUnitTest.php b/WordPress/Tests/WP/CronIntervalUnitTest.php
index 81f02c2768..e70db87175 100644
--- a/WordPress/Tests/WP/CronIntervalUnitTest.php
+++ b/WordPress/Tests/WP/CronIntervalUnitTest.php
@@ -67,6 +67,7 @@ public function getWarningList() {
 			290 => 1,
 			327 => 1,
 			328 => 1,
+			329 => 1,
 		);
 	}
 }
diff --git a/WordPress/Tests/WP/DiscouragedConstantsUnitTest.inc b/WordPress/Tests/WP/DiscouragedConstantsUnitTest.inc
index ea8ae72524..bed0914d53 100644
--- a/WordPress/Tests/WP/DiscouragedConstantsUnitTest.inc
+++ b/WordPress/Tests/WP/DiscouragedConstantsUnitTest.inc
@@ -102,3 +102,11 @@ enum ContainsConst {
 }
 
 echo HEADER_TEXTCOLOR::$var; // OK.
+
+/*
+ * Safeguard correct handling of all types of namespaced function calls.
+ */
+\define( 'STYLESHEETPATH', 'something' ); // Bad.
+\MyNamespace\define( 'STYLESHEETPATH', 'something' ); // Ok.
+MyNamespace\define( 'STYLESHEETPATH', 'something' ); // Ok.
+namespace\define( 'STYLESHEETPATH', 'something' ); // Ok.
diff --git a/WordPress/Tests/WP/DiscouragedConstantsUnitTest.php b/WordPress/Tests/WP/DiscouragedConstantsUnitTest.php
index e27fd838c2..138d0eb4ef 100644
--- a/WordPress/Tests/WP/DiscouragedConstantsUnitTest.php
+++ b/WordPress/Tests/WP/DiscouragedConstantsUnitTest.php
@@ -36,26 +36,27 @@ public function getErrorList() {
 	 */
 	public function getWarningList() {
 		return array(
-			50 => 1,
-			51 => 1,
-			52 => 1,
-			53 => 1,
-			54 => 1,
-			55 => 1,
-			56 => 1,
-			57 => 1,
-			58 => 1,
-			59 => 1,
-			60 => 1,
-			61 => 1,
-			63 => 1,
-			64 => 1,
-			66 => 1,
-			67 => 1,
-			71 => 1,
-			72 => 1,
-			83 => 1,
-			88 => 1,
+			50  => 1,
+			51  => 1,
+			52  => 1,
+			53  => 1,
+			54  => 1,
+			55  => 1,
+			56  => 1,
+			57  => 1,
+			58  => 1,
+			59  => 1,
+			60  => 1,
+			61  => 1,
+			63  => 1,
+			64  => 1,
+			66  => 1,
+			67  => 1,
+			71  => 1,
+			72  => 1,
+			83  => 1,
+			88  => 1,
+			109 => 1,
 		);
 	}
 }