diff --git a/.settings/edu.umd.cs.findbugs.core.prefs b/.settings/edu.umd.cs.findbugs.core.prefs
index b8ac7bfb7ad44dc4b107508cb0c89eae06a59037..dcab7ec0a4ebe79c8cd787225f5cf33a0850d331 100644
--- a/.settings/edu.umd.cs.findbugs.core.prefs
+++ b/.settings/edu.umd.cs.findbugs.core.prefs
@@ -1,5 +1,5 @@
 #FindBugs User Preferences
-#Mon Jul 27 14:55:35 CEST 2015
+#Thu Jul 30 13:22:16 CEST 2015
 detector_threshold=2
 effort=max
 excludefilter0=.fbExcludeFilterFile|true
diff --git a/src/main/java/teetime/framework/AbstractRunnableStage.java b/src/main/java/teetime/framework/AbstractRunnableStage.java
index 3057c121cc04fc684385fe8bf085e345f9619a27..2fe5827caffa46a45cf1ab60913a66916586b8c2 100644
--- a/src/main/java/teetime/framework/AbstractRunnableStage.java
+++ b/src/main/java/teetime/framework/AbstractRunnableStage.java
@@ -29,6 +29,10 @@ abstract class AbstractRunnableStage implements Runnable {
 	protected final Logger logger;
 
 	public AbstractRunnableStage(final Stage stage) {
+		if (stage == null) {
+			throw new IllegalArgumentException("Argument stage may not be null");
+		}
+
 		this.stage = stage;
 		this.logger = LoggerFactory.getLogger(stage.getClass());