diff --git a/prism/src/parser/PrismParser.java b/prism/src/parser/PrismParser.java
index 33445136..551c1a44 100644
--- a/prism/src/parser/PrismParser.java
+++ b/prism/src/parser/PrismParser.java
@@ -108,7 +108,6 @@ public class PrismParser implements PrismParserConstants {
                         }
                 }
                 catch (PrismLangException e) {
-                	e.printStackTrace();
                         System.out.println("Error in "+src+": " + e.getMessage()+"."); System.exit(1);
                 }
                 catch (FileNotFoundException e) {
diff --git a/prism/src/parser/PrismParser.jj b/prism/src/parser/PrismParser.jj
index bcdc3eae..34e2774c 100644
--- a/prism/src/parser/PrismParser.jj
+++ b/prism/src/parser/PrismParser.jj
@@ -119,7 +119,7 @@ public class PrismParser
 				System.out.println("LTL formula: " + expr.toString());
 				System.out.print("Tree:\n=====\n" + expr.toTreeString());
 				expr.typeCheck();
-				expr.semanticCheck();
+				//expr.semanticCheck();
 				System.out.println("Type: " + expr.getType().getTypeString());
 				boolean pnf = Expression.isPositiveNormalFormLTL(expr);
 				System.out.println("Positive normal form: " + pnf);