diff --git a/src/wp-admin/includes/class-wp-list-table.php b/src/wp-admin/includes/class-wp-list-table.php
index 3c7e6b3a3f..bc6f0a7fd8 100644
--- a/src/wp-admin/includes/class-wp-list-table.php
+++ b/src/wp-admin/includes/class-wp-list-table.php
@@ -946,12 +946,12 @@ class WP_List_Table {
 	}
 
 	/**
-	 * Get a list of sortable columns. The format is:
-	 * 'internal-name' => 'orderby'
-	 * or
-	 * 'internal-name' => array( 'orderby', true )
+	 * Get a list of sortable columns.
 	 *
-	 * The second format will make the initial sorting order be descending
+	 * The format is:
+	 * - `'internal-name' => 'orderby'`
+	 * - `'internal-name' => array( 'orderby', 'asc' )` - The second element set the initial sorting order.
+	 * - `'internal-name' => array( 'orderby', true )` - The second element will make the initial sorting order be descending.
 	 *
 	 * @since 3.1.0
 	 *
@@ -1161,9 +1161,13 @@ class WP_List_Table {
 					$class[] = 'sorted';
 					$class[] = $current_order;
 				} else {
-					$order   = $desc_first ? 'desc' : 'asc';
+					if ( in_array( strtolower( $desc_first ), array( 'desc', 'asc' ), true ) ) {
+						$order = 'asc' === strtolower( $desc_first ) ? 'desc' : 'asc';
+					} else {
+						$order = $desc_first ? 'desc' : 'asc';
+					}
 					$class[] = 'sortable';
-					$class[] = $desc_first ? 'asc' : 'desc';
+					$class[] = 'desc' === $order ? 'asc' : 'desc';
 				}
 
 				$column_display_name = '<a href="' . esc_url( add_query_arg( compact( 'orderby', 'order' ), $current_url ) ) . '"><span>' . $column_display_name . '</span><span class="sorting-indicator"></span></a>';
diff --git a/tests/phpunit/tests/admin/includesListTable.php b/tests/phpunit/tests/admin/includesListTable.php
index 9edbea1793..56b3be2d20 100644
--- a/tests/phpunit/tests/admin/includesListTable.php
+++ b/tests/phpunit/tests/admin/includesListTable.php
@@ -293,4 +293,77 @@ class Tests_Admin_includesListTable extends WP_UnitTestCase {
 
 		$this->assertNotContains( 'id="delete_all"', $output );
 	}
+
+	/**
+	 * @ticket 45089
+	 */
+	public function test_sortable_columns() {
+		require_once ABSPATH . 'wp-admin/includes/class-wp-comments-list-table.php';
+
+		$override_sortable_columns = array(
+			'author'   => array( 'comment_author', true ),
+			'response' => 'comment_post_ID',
+			'date'     => array( 'comment_date', 'dEsC' ), // The ordering support should be case insensitive.
+		);
+
+		// Stub the get_sortable_columns() method.
+		$object = $this->getMockBuilder( 'WP_Comments_List_Table' )
+			->setConstructorArgs( array( array( 'screen' => 'edit-comments' ) ) )
+			->setMethods( array( 'get_sortable_columns' ) )
+			->getMock();
+
+		// Change the null return value of the stubbed get_sortable_columns() method.
+		$object->method( 'get_sortable_columns' )
+			->willReturn( $override_sortable_columns );
+
+		$output = get_echo( array( $object, 'print_column_headers' ) );
+
+		$this->assertContains( '?orderby=comment_author&#038;order=desc', $output, 'Mismatch of the default link ordering for comment author column. Should be desc.' );
+		$this->assertContains( 'column-author sortable asc', $output, 'Mismatch of CSS classes for the comment author column.' );
+
+		$this->assertContains( '?orderby=comment_post_ID&#038;order=asc', $output, 'Mismatch of the default link ordering for comment response column. Should be asc.' );
+		$this->assertContains( 'column-response sortable desc', $output, 'Mismatch of CSS classes for the comment post ID column.' );
+
+		$this->assertContains( '?orderby=comment_date&#038;order=asc', $output, 'Mismatch of the default link ordering for comment author column. Should be asc.' );
+		$this->assertContains( 'column-date sortable desc', $output, 'Mismatch of CSS classes for the comment date column.' );
+	}
+
+	/**
+	 * @ticket 45089
+	 */
+	public function test_sortable_columns_with_current_ordering() {
+		require_once ABSPATH . 'wp-admin/includes/class-wp-comments-list-table.php';
+
+		$override_sortable_columns = array(
+			'author'   => array( 'comment_author', false ),
+			'response' => 'comment_post_ID',
+			'date'     => array( 'comment_date', 'asc' ), // We will override this with current ordering.
+		);
+
+		// Current ordering.
+		$_GET['orderby'] = 'comment_date';
+		$_GET['order']   = 'desc';
+
+		// Stub the get_sortable_columns() method.
+		$object = $this->getMockBuilder( 'WP_Comments_List_Table' )
+			->setConstructorArgs( array( array( 'screen' => 'edit-comments' ) ) )
+			->setMethods( array( 'get_sortable_columns' ) )
+			->getMock();
+
+		// Change the null return value of the stubbed get_sortable_columns() method.
+		$object->method( 'get_sortable_columns' )
+			->willReturn( $override_sortable_columns );
+
+		$output = get_echo( array( $object, 'print_column_headers' ) );
+
+		$this->assertContains( '?orderby=comment_author&#038;order=asc', $output, 'Mismatch of the default link ordering for comment author column. Should be asc.' );
+		$this->assertContains( 'column-author sortable desc', $output, 'Mismatch of CSS classes for the comment author column.' );
+
+		$this->assertContains( '?orderby=comment_post_ID&#038;order=asc', $output, 'Mismatch of the default link ordering for comment response column. Should be asc.' );
+		$this->assertContains( 'column-response sortable desc', $output, 'Mismatch of CSS classes for the comment post ID column.' );
+
+		$this->assertContains( '?orderby=comment_date&#038;order=asc', $output, 'Mismatch of the current link ordering for comment date column. Should be asc.' );
+		$this->assertContains( 'column-date sorted desc', $output, 'Mismatch of CSS classes for the comment date column.' );
+	}
+
 }