diff --git a/ec2/spark_ec2.py b/ec2/spark_ec2.py
index ddd3d5aa6d93a526820d35b256c5baca2f4c653f..48eb8ca3c18c24d39030896d00dc97a78de8bb5f 100755
--- a/ec2/spark_ec2.py
+++ b/ec2/spark_ec2.py
@@ -371,6 +371,7 @@ def get_num_disks(instance_type):
   # From http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/index.html?InstanceStorage.html
   disks_by_instance = {
     "m1.small":    1,
+    "m1.medium":   1,
     "m1.large":    2,
     "m1.xlarge":   4,
     "t1.micro":    1,