diff --git a/botocore/handlers.py b/botocore/handlers.py
index 7c9673cf9d..40dd7ad776 100644
--- a/botocore/handlers.py
+++ b/botocore/handlers.py
@@ -372,8 +372,11 @@ def parse_get_bucket_location(parsed, http_response, **kwargs):
 
 def base64_encode_user_data(params, **kwargs):
     if 'UserData' in params:
+        if isinstance(params['UserData'], six.text_type):
+            # Encode it to bytes if it is text.
+            params['UserData'] = params['UserData'].encode('utf-8')
         params['UserData'] = base64.b64encode(
-            params['UserData'].encode('utf-8')).decode('utf-8')
+            params['UserData']).decode('utf-8')
 
 
 def fix_route53_ids(params, model, **kwargs):
diff --git a/tests/unit/test_ec2_operations.py b/tests/unit/test_ec2_operations.py
index 9e1244efa1..ece9054779 100644
--- a/tests/unit/test_ec2_operations.py
+++ b/tests/unit/test_ec2_operations.py
@@ -86,19 +86,6 @@ def test_request_spot_instances(self):
                   'LaunchSpecification.BlockDeviceMapping.4.VirtualName': 'ephemeral3'}
         self.assert_params_serialize_to('ec2.RequestSpotInstances', params, result)
 
-    def test_run_instances_userdata(self):
-        user_data = 'This is a test'
-        b64_user_data = base64.b64encode(six.b(user_data)).decode('utf-8')
-        op = self.ec2.get_operation('RunInstances')
-        params = dict(image_id='img-12345678',
-                      min_count=1, max_count=5, user_data=user_data)
-        result = {'ImageId': 'img-12345678',
-                  'MinCount': 1,
-                  'MaxCount': 5,
-                  'UserData': b64_user_data}
-        # TODO: We need to base64 decode this!  Needs a customization
-        #self.assert_params_serialize_to('ec2.RunInstances', params, result)
-
     def test_authorize_security_groups_ingress(self):
         params = dict(
             group_name='MyGroup',
diff --git a/tests/unit/test_handlers.py b/tests/unit/test_handlers.py
index 07cf5b070b..090b06270c 100644
--- a/tests/unit/test_handlers.py
+++ b/tests/unit/test_handlers.py
@@ -247,6 +247,37 @@ def test_route53_resource_id_missing_input_shape(self):
 
         self.assertEqual(params['HostedZoneId'], '/hostedzone/ABC123')
 
+    def test_run_instances_userdata(self):
+        user_data = 'This is a test'
+        b64_user_data = base64.b64encode(six.b(user_data)).decode('utf-8')
+        event = self.session.create_event(
+            'before-parameter-build', 'ec2', 'RunInstances')
+        params = dict(ImageId='img-12345678',
+                      MinCount=1, MaxCount=5, UserData=user_data)
+        self.session.emit(event, params=params)
+        result = {'ImageId': 'img-12345678',
+                  'MinCount': 1,
+                  'MaxCount': 5,
+                  'UserData': b64_user_data}
+        self.assertEqual(params, result)
+
+    def test_run_instances_userdata_blob(self):
+        # Ensure that binary can be passed in as user data.
+        # This is valid because you can send gzip compressed files as
+        # user data.
+        user_data = b'\xc7\xa9This is a test'
+        b64_user_data = base64.b64encode(user_data).decode('utf-8')
+        event = self.session.create_event(
+            'before-parameter-build', 'ec2', 'RunInstances')
+        params = dict(ImageId='img-12345678',
+                      MinCount=1, MaxCount=5, UserData=user_data)
+        self.session.emit(event, params=params)
+        result = {'ImageId': 'img-12345678',
+                  'MinCount': 1,
+                  'MaxCount': 5,
+                  'UserData': b64_user_data}
+        self.assertEqual(params, result)
+
     def test_fix_s3_host_initial(self):
         endpoint = mock.Mock(region_name='us-west-2')
         request = AWSRequest(