Index: wp-admin/upload-functions.php
===================================================================
--- wp-admin/upload-functions.php	(revision 4425)
+++ wp-admin/upload-functions.php	(working copy)
@@ -13,9 +13,9 @@
 	
 	$class = 'text';
 	$innerHTML = get_attachment_innerHTML( $id, false, $dims );
-	if ( $image_src = strstr($innerHTML, 'src="') ) {
-		$image_src = explode('"', $image_src);
-		$image_src = $image_src[1];
+	if ( $image_src = strstr($innerHTML, 'src=') ) {
+		preg_match("/src=(\"|')(.+?)\\1/", $image_src, $matches);
+		$image_src = $matches[2];
 		$image_rel = wp_make_link_relative($image_src);
 		$class = 'image';
 		$innerHTML = ' ' . str_replace($image_src, $image_rel, $innerHTML);