diff --git a/moto/iam/models.py b/moto/iam/models.py
index bc71df6d9..62d63cf2f 100644
--- a/moto/iam/models.py
+++ b/moto/iam/models.py
@@ -85,8 +85,8 @@ class VirtualMfaDevice(object):
         self.base32_string_seed = base64.b64encode(
             random_base32_string.encode("ascii")
         ).decode("ascii")
-        self.qr_code_png = base64.b64encode(
-            os.urandom(64)
+        self.qr_code_png = base64.b64encode(os.urandom(64)).decode(
+            "ascii"
         )  # this would be a generated PNG
 
         self.enable_date = None
diff --git a/moto/iam/responses.py b/moto/iam/responses.py
index 9a149b65f..178d19a8d 100644
--- a/moto/iam/responses.py
+++ b/moto/iam/responses.py
@@ -2110,6 +2110,9 @@ LIST_MFA_DEVICES_TEMPLATE = """<ListMFADevicesResponse>
          <member>
             <UserName>{{ user_name }}</UserName>
             <SerialNumber>{{ device.serial_number }}</SerialNumber>
+            {% if device.enable_date %}
+            <EnableDate>{{ device.enabled_iso_8601 }}</EnableDate>
+            {% endif %}
          </member>
         {% endfor %}
       </MFADevices>