diff --git a/prism/src/prism/Preprocessor.java b/prism/src/prism/Preprocessor.java
index dd6e38b6..3b875b05 100644
--- a/prism/src/prism/Preprocessor.java
+++ b/prism/src/prism/Preprocessor.java
@@ -427,7 +427,7 @@ public class Preprocessor
 			}
 		}
 		catch (PrismException e) {
-			System.out.println("Error: " + e.getMessage());
+			System.err.println("Error: " + e.getMessage());
 		}
 	}
 }