Index: wp-testcase/test_includes_formatting.php
===================================================================
--- wp-testcase/test_includes_formatting.php	(revision 435)
+++ wp-testcase/test_includes_formatting.php	(working copy)
@@ -469,6 +469,12 @@
 		$this->assertEquals(' “Testing”', wptexturize(' "Testing"'));
 		$this->assertEquals('&“Testing”', wptexturize('&"Testing"'));
 	}
+
+	//WP Ticket #18575
+	function test_unbalacned_brackets() {
+		$this->knownWPBug(18575);
+		$this->assertEquals('[hello <a href="foo[bar](\'baz\')">world</a>', wptexturize('[hello <a href="foo[bar](\'baz\')">world</a>'));
+	}
 }
 
 class TestCleanUrl extends WPTestCase {