diff --git a/amrun.cabal b/amrun.cabal
--- a/amrun.cabal
+++ b/amrun.cabal
@@ -1,5 +1,5 @@
 Name:                amrun
-Version:             0.0.0.2
+Version:             0.0.0.3
 Synopsis:            Interpreter for AM
 Description:         The package contains an interpreter for the AM-Language that is introduced in the basic programming course \"Algorithmisches Denken und imperative Programmierung\" (WS 2011/12 and later) at the University of Bonn.
 License:             GPL
diff --git a/src/amrun.hs b/src/amrun.hs
--- a/src/amrun.hs
+++ b/src/amrun.hs
@@ -5,6 +5,7 @@
 import System.IO
 import System.IO.Unsafe
 import Control.DeepSeq
+import Data.Char (toUpper)
 
 import Text.Parsec
 import Text.ParserCombinators.Parsec.Char
@@ -138,10 +139,10 @@
 
 commandParser :: CharParser Int Command
 commandParser = do {
- cmd <- ((many1 upper) <|> lookAhead ((space <|> char ';') >> return "")) <?> "expected command (did you write upper case letters?)";
+ cmd <- ((many1 letter) <|> lookAhead ((space <|> char ';') >> return "")) <?> "expected command";
  spaces <?> "";
- let noArgCmd = readCmd cmd
-     oneArgCmd = readCmd' cmd
+ let noArgCmd = readCmd (map toUpper cmd)
+     oneArgCmd = readCmd' (map toUpper cmd)
  in
  case noArgCmd of
    Just c -> return c