diff --git a/source/net/sourceforge/filebot/format/ExpressionFormat.lib.groovy b/source/net/sourceforge/filebot/format/ExpressionFormat.lib.groovy
index 385d0e89..24e09b72 100644
--- a/source/net/sourceforge/filebot/format/ExpressionFormat.lib.groovy
+++ b/source/net/sourceforge/filebot/format/ExpressionFormat.lib.groovy
@@ -41,10 +41,10 @@ String.metaClass.pad = Number.metaClass.pad = { length = 2, padding = "0" -> del
 /**
  * Return a substring matching the given pattern or break.
  */
-String.metaClass.match = { String pattern, int matchGroup = 0 -> 
+String.metaClass.match = { String pattern, matchGroup = null -> 
 	def matcher = Pattern.compile(pattern, Pattern.CASE_INSENSITIVE | Pattern.UNICODE_CASE).matcher(delegate)
 	if (matcher.find())
-		return matcher.group(matchGroup)
+		return matcher.groupCount() > 0 && matchGroup == null ? matcher.group(1) : matcher.group(matchGroup ?: 0)
 	else
 		throw new Exception("Match failed")
 }