diff --git wp-includes/class.wp-styles.php wp-includes/class.wp-styles.php
index ecc0bb9..0435ad6 100644
--- wp-includes/class.wp-styles.php
+++ wp-includes/class.wp-styles.php
@@ -62,8 +62,13 @@ class WP_Styles extends WP_Dependencies {
 
 		$end_cond = $tag = '';
 		if ( isset($this->registered[$handle]->extra['conditional']) && $this->registered[$handle]->extra['conditional'] ) {
-			$tag .= "<!--[if {$this->registered[$handle]->extra['conditional']}]>\n";
-			$end_cond = "<![endif]-->\n";
+			$tag .= "<!--[if {$this->registered[$handle]->extra['conditional']}]>";
+			if ( $this->registered[$handle]->extra['conditional'][0] == '!' ) {
+				$tag .= '<!-->';
+				$end_cond = '<!--';
+			}
+			$tag .= "\n";
+			$end_cond .= "<![endif]-->\n";
 		}
 
 		$tag .= apply_filters( 'style_loader_tag', "<link rel='$rel' id='$handle-css' $title href='$href' type='text/css' media='$media' />\n", $handle );