diff -r b4e09ae24bf1 -r 6c4efed2dbdd scriptreader.cxx
--- a/scriptreader.cxx	Mon Jul 16 04:15:49 2012 +0300
+++ b/scriptreader.cxx	Mon Jul 16 04:26:27 2012 +0300
@@ -273,9 +273,19 @@
 }
 
 void ScriptReader::MustNumber () {
+	str num;
 	MustNext ();
-	if (!token.isnumber())
-		ParserError ("expected a number, got `%s`", token.chars());
+	num += token;
+	
+	// Cater for a possible minus sign, since it
+	// breaks the token, read a new one with the number.
+	if (!token.compare ("-")) {
+		MustNext ();
+		num += token;
+	}
+	
+	if (!num.isnumber())
+		ParserError ("expected a number, got `%s`", num.chars());
 }
 
 void ScriptReader::MustBool () {