diff --git a/createthumb.php b/createthumb.php
index a9c3ee6..28b40f8 100644
--- a/createthumb.php
+++ b/createthumb.php
@@ -60,29 +60,9 @@ function flipHorizontal(&$img) {
 	}
 }
 
-function str_split_php4( $text, $split = 1 ) {
-	// place each character of the string into and array
-	$array = array();
-	for ( $i=0; $i < strlen( $text ); )
-	{
-		$key = NULL;
-		for ( $j = 0; $j < $split; $j++, $i++ )
-		{
-			$key .= $text[$i];
-		}
-		array_push( $array, $key );
-	}
-	return $array;
-}
-
-function sanitize($name)
-{
-	// Sanitize image filename (taken from http://iamcam.wordpress.com/2007/03/20/clean-file-names-using-php-preg_replace/ )
-	$fname=$name;
-	$replace="_";
-	$pattern="/([[:alnum:]_\.-]*)/";
-	$fname=str_replace(str_split_php4(preg_replace($pattern,$replace,$fname)),$replace,$fname);
-	return $fname;
+function sanitize($name) {
+// note: this allows for collisions
+	return preg_replace("/[^[:alnum:]_.-]/", "_", $name);
 }
 
 // Make sure the "thumbs" directory exists.