diff --git a/stratosphere-compiler/src/main/java/eu/stratosphere/compiler/contextcheck/ContextChecker.java b/stratosphere-compiler/src/main/java/eu/stratosphere/compiler/contextcheck/ContextChecker.java
index b6b7536848d68e886beac297a841c221035cb6e7..91775a51ad55e56c623f48cc6ab82a763f8cd92b 100644
--- a/stratosphere-compiler/src/main/java/eu/stratosphere/compiler/contextcheck/ContextChecker.java
+++ b/stratosphere-compiler/src/main/java/eu/stratosphere/compiler/contextcheck/ContextChecker.java
@@ -16,6 +16,8 @@ package eu.stratosphere.compiler.contextcheck;
 import java.util.HashSet;
 import java.util.Set;
 
+import com.google.common.base.Preconditions;
+
 import eu.stratosphere.api.common.InvalidProgramException;
 import eu.stratosphere.api.common.Plan;
 import eu.stratosphere.api.common.operators.BulkIteration;
@@ -52,9 +54,10 @@ public class ContextChecker implements Visitor<Operator> {
 	 * thrown.
 	 * 
 	 * @param plan
-	 *        The PACT plan to check.
+	 *        The plan to check.
 	 */
 	public void check(Plan plan) {
+		Preconditions.checkNotNull(plan, "The passed plan is null.");
 		this.visitedNodes.clear();
 		plan.accept(this);
 	}
diff --git a/stratosphere-examples/stratosphere-scala-examples/src/main/scala/eu/stratosphere/examples/scala/wordcount/WordCount.scala b/stratosphere-examples/stratosphere-scala-examples/src/main/scala/eu/stratosphere/examples/scala/wordcount/WordCount.scala
index d77507d3607345e619f436eddc28ed658ef923b8..e3083aa3030aa25f932d60fe416ff7ff0bf3d5f3 100644
--- a/stratosphere-examples/stratosphere-scala-examples/src/main/scala/eu/stratosphere/examples/scala/wordcount/WordCount.scala
+++ b/stratosphere-examples/stratosphere-scala-examples/src/main/scala/eu/stratosphere/examples/scala/wordcount/WordCount.scala
@@ -44,6 +44,10 @@ class WordCount extends Program with ProgramDescription with Serializable {
     "Parameters: <numSubStasks> <input> <output>"
   }
   override def getPlan(args: String*) = {
+    if (args.size < 3) {
+      println(getDescription)
+      System.exit(1);
+    }
     getScalaPlan(args(0).toInt, args(1), args(2))
   }
 }
diff --git a/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/jobmanager/JobManager.java b/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/jobmanager/JobManager.java
index d256d5176be04b7918c2f185007d6e8faab6e459..f8cbbe1e161f57aa4917590b9602b655e52dba6c 100644
--- a/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/jobmanager/JobManager.java
+++ b/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/jobmanager/JobManager.java
@@ -359,9 +359,12 @@ public class JobManager implements DeploymentManager, ExtendedManagementProtocol
 		
 		// Clean up is triggered through a shutdown hook
 		// freeze this thread to keep the JVM alive (the job manager threads are daemon threads)
-		try {
-			new Object().wait();
-		} catch (InterruptedException e) {}
+		Object w = new Object();
+		synchronized (w) {
+			try {
+				w.wait();
+			} catch (InterruptedException e) {}
+		}
 	}
 	
 	@SuppressWarnings("static-access")
diff --git a/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/taskmanager/TaskManager.java b/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/taskmanager/TaskManager.java
index 4b832638063c7e2e7015330cc420d4fc7e052871..1ea5b1be626c47fe2b83ed0a2cec57e4b7ce7a23 100644
--- a/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/taskmanager/TaskManager.java
+++ b/stratosphere-runtime/src/main/java/eu/stratosphere/nephele/taskmanager/TaskManager.java
@@ -556,8 +556,9 @@ public class TaskManager implements TaskOperationProtocol {
 			socket.bind(bindP);
 			socket.connect(toSocket, timeout);
 		} catch (Exception ex) {
+			LOG.info("Failed to determine own IP address from '" + fromAddress + "': " + ex.getMessage());
 			if (LOG.isDebugEnabled()) {
-				LOG.debug("Failed on this address: " + ex.getMessage());
+				LOG.debug("Failed with exception", ex);
 			}
 			connectable = false;
 		} finally {