diff --git a/ec2/spark_ec2.py b/ec2/spark_ec2.py
index 0ce5ce867f2b63aeb48b7f9934b5cfd7540b8c9f..413fcf26953d4a5f478aeacfae81544e4d13447d 100755
--- a/ec2/spark_ec2.py
+++ b/ec2/spark_ec2.py
@@ -236,7 +236,7 @@ def launch_cluster(conn, opts, cluster_name):
                                       die_on_error=False)
   if any(active_nodes):
     print >> stderr, ("ERROR: There are already instances running in " +
-        "group %s, %s or %s" % (master_group.name, slave_group.name))
+        "group %s or %s" % (master_group.name, slave_group.name))
     sys.exit(1)
 
   # Figure out Spark AMI