diff --git a/tests/phpunit/tests/cache.php b/tests/phpunit/tests/cache.php
index 548f185fa9..79654fcaa9 100644
--- a/tests/phpunit/tests/cache.php
+++ b/tests/phpunit/tests/cache.php
@@ -324,7 +324,7 @@ class Tests_Cache extends WP_UnitTestCase {
 		wp_cache_replace( $key, $val2 );
 		$this->assertSame( $val2, wp_cache_get( $key ) );
 
-		// Non-existant key should fail.
+		// Non-existent key should fail.
 		$this->assertFalse( wp_cache_replace( $fake_key, $val1 ) );
 
 		// Make sure $fake_key is not stored.
diff --git a/tests/phpunit/tests/cron.php b/tests/phpunit/tests/cron.php
index 67a0f2bc22..36b974cf1a 100644
--- a/tests/phpunit/tests/cron.php
+++ b/tests/phpunit/tests/cron.php
@@ -245,7 +245,7 @@ class Tests_Cron extends WP_UnitTestCase {
 		$hook           = __FUNCTION__;
 		$unrelated_hook = __FUNCTION__ . '_two';
 
-		// Attempt to clear schedule on non-existant hook.
+		// Attempt to clear schedule on non-existent hook.
 		$unschedule_hook = wp_unschedule_hook( $hook );
 		$this->assertSame( 0, $unschedule_hook );
 		$this->assertFalse( wp_next_scheduled( $hook ) );
diff --git a/tests/phpunit/tests/mail.php b/tests/phpunit/tests/mail.php
index fabeb092dc..dfa82988e5 100644
--- a/tests/phpunit/tests/mail.php
+++ b/tests/phpunit/tests/mail.php
@@ -171,7 +171,7 @@ class Tests_Mail extends WP_UnitTestCase {
 		$this->assertTrue( wp_mail( 'valid@address.com', 'subject', 'body' ) );
 
 		// Non-fatal errors.
-		$this->assertTrue( wp_mail( 'valid@address.com', 'subject', 'body', "Cc: invalid-address\nBcc: @invalid.address", ABSPATH . '/non-existant-file.html' ) );
+		$this->assertTrue( wp_mail( 'valid@address.com', 'subject', 'body', "Cc: invalid-address\nBcc: @invalid.address", ABSPATH . '/non-existent-file.html' ) );
 
 		// Fatal errors.
 		$this->assertFalse( wp_mail( 'invalid.address', 'subject', 'body', '', array() ) );
diff --git a/tests/phpunit/tests/rest-api/rest-post-meta-fields.php b/tests/phpunit/tests/rest-api/rest-post-meta-fields.php
index 0953a9fd41..2b75162976 100644
--- a/tests/phpunit/tests/rest-api/rest-post-meta-fields.php
+++ b/tests/phpunit/tests/rest-api/rest-post-meta-fields.php
@@ -1053,7 +1053,7 @@ class WP_Test_REST_Post_Meta_Fields extends WP_Test_REST_TestCase {
 	}
 
 	/**
-	 * Ensure deleting non-existant meta data behaves gracefully.
+	 * Ensure deleting non-existent meta data behaves gracefully.
 	 *
 	 * @ticket 52787
 	 * @dataProvider data_delete_does_not_trigger_error_if_no_meta_values