diff --git a/moto/ec2/responses/amis.py b/moto/ec2/responses/amis.py
index 74767aa6..d9be7781 100755
--- a/moto/ec2/responses/amis.py
+++ b/moto/ec2/responses/amis.py
@@ -115,7 +115,7 @@ DESCRIBE_IMAGES_RESPONSE = """<DescribeImagesResponse xmlns="http://ec2.amazonaw
           {% endif %}
           <description>{{ image.description }}</description>
           <rootDeviceType>ebs</rootDeviceType>
-          <rootDeviceName>/dev/sda</rootDeviceName>
+          <rootDeviceName>/dev/sda1</rootDeviceName>
           <blockDeviceMapping>
             <item>
               <deviceName>/dev/sda1</deviceName>
diff --git a/tests/test_ec2/test_amis.py b/tests/test_ec2/test_amis.py
index ed251f52..cf9f73f0 100755
--- a/tests/test_ec2/test_amis.py
+++ b/tests/test_ec2/test_amis.py
@@ -57,6 +57,10 @@ def test_ami_create_and_delete():
         "Auto-created snapshot for AMI {0}".format(image.id))
     snapshot.volume_id.should.equal(volume.id)
 
+    # root device should be in AMI's block device mappings
+    root_mapping = image.block_device_mapping.get(image.root_device_name)
+    root_mapping.should_not.be.none
+
     # Deregister
     with assert_raises(EC2ResponseError) as ex:
         success = conn.deregister_image(image_id, dry_run=True)