diff --git a/sources/zweic/Analyzer.scala b/sources/zweic/Analyzer.scala
index a9a3f76..2ae6212 100755
--- a/sources/zweic/Analyzer.scala
+++ b/sources/zweic/Analyzer.scala
@@ -76,6 +76,11 @@
 
 			val paramtypes = for ( val f <- args ) yield {
 				//TODO: check that there isn't already a class field with the same name
+				myVarScope.get(f.name.name) match {
+					case Some(m) =>
+						Report.error(f.pos, "an argument with the name '" + f.name.name +  "' exists already");
+					case None => ()
+				}
 				val at = analyzeType(f.typ);
 				f.name.sym = VarSymbol(f.pos, f.name.name, at);
 				myVarScope = myVarScope + f.name.name -> f.name.sym.asInstanceOf[VarSymbol];