Index: src/Parser/lex.ll
===================================================================
--- src/Parser/lex.ll	(revision 1319235d9279d8722331159c04581274d03fdbf6)
+++ src/Parser/lex.ll	(revision a8615fd179021a33f58c96359b2feef164ca41bc)
@@ -464,5 +464,5 @@
 void yyerror( const char * errmsg ) {
 	SemanticErrorThrow = true;
-	cout << (yyfilename ? yyfilename : "*unknown file*") << ':' << yylineno << ':' << column - yyleng + 1
+	cerr << (yyfilename ? yyfilename : "*unknown file*") << ':' << yylineno << ':' << column - yyleng + 1
 		 << ": " << ErrorHelpers::error_str() << errmsg << " at token \"" << (yytext[0] == '\0' ? "EOF" : yytext) << '"' << endl;
 }