diff --git a/server/Pipfile b/server/Pipfile
index 0b45044..a5d9df6 100644
--- a/server/Pipfile
+++ b/server/Pipfile
@@ -8,19 +8,19 @@ flask = ">=1.0,<1.1"
 flask-sqlalchemy = ">=2.3,<2.4"
 flask-migrate = ">=2.1,<2.2"
 pynacl = ">=1.2,<1.3"
-click = "*"
-"rfc3339" = "*"
-"iso8601" = "*"
+click = ">=6.7,<6.8"
+rfc3339 = ">=6.0,<6.1"
+iso8601 = ">=0.1,<0.2"
 
 [dev-packages]
-python-dotenv = "*"
-pytest = "*"
-coverage = "*"
-pycodestyle = "*"
-mypy = "*"
-mock = "*"
-pylint = "*"
-pydocstyle = "*"
+python-dotenv = ">=0.8,<0.9"
+pytest = ">=3.6<3.7"
+coverage = ">=4.5,<4.6"
+pycodestyle = ">=2.4,<2.5"
+mypy = ">=0.620,<1.0"
+mock = ">=2.0,<2.1"
+pylint = ">=2.0,<2.1"
+pydocstyle = ">=2.1,<2.2"
 
 [requires]
 python_version = "3.6"
diff --git a/server/Pipfile.lock b/server/Pipfile.lock
index b322b98..55d3b62 100644
--- a/server/Pipfile.lock
+++ b/server/Pipfile.lock
@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "b0d90486a769e10025b310d91ee6e7023af9c9e303fce92df9a3541004e3256c"
+            "sha256": "3ce19ff3ec099304cd32e4cb6868cbc317ec05da27c6020ebc5f35262f2d9613"
         },
         "pipfile-spec": 6,
         "requires": {
diff --git a/server/atheneum/service/patch_service.py b/server/atheneum/service/patch_service.py
index d30b579..1a42cff 100644
--- a/server/atheneum/service/patch_service.py
+++ b/server/atheneum/service/patch_service.py
@@ -9,9 +9,9 @@ from atheneum.service import validation_service
 
 def get_patch_fields(patch_json: Dict[str, Any]) -> Set[str]:
     """Convert json fields to python fields."""
-    return set([
+    return {
         transformation_service.convert_key_from_json(key) for key in
-        patch_json.keys()])
+        patch_json.keys()}
 
 
 def perform_patch(request_user: User,
@@ -108,9 +108,8 @@ def patch(
             patch_model,
             model_attributes,
             patched_fields)
-    else:
-        raise ValueError(
-            'Model types "{}" and "{}" do not match'.format(
-                original_model.__class__.__name__,
-                patch_model.__class__.__name__
-            ))
+    raise ValueError(
+        'Model types "{}" and "{}" do not match'.format(
+            original_model.__class__.__name__,
+            patch_model.__class__.__name__
+        ))
diff --git a/server/atheneum/service/validation_service.py b/server/atheneum/service/validation_service.py
index 0583b5f..2c0bfdd 100644
--- a/server/atheneum/service/validation_service.py
+++ b/server/atheneum/service/validation_service.py
@@ -23,10 +23,9 @@ def get_changable_attribute_names(model: Type[db.Model]) -> Set[str]:
     if class_name in _changable_attribute_names:
         return _changable_attribute_names[class_name]
 
-    model_attributes = set([prop.key for prop in
-                            orm.class_mapper(
-                                model.__class__).iterate_properties
-                            if isinstance(prop, orm.ColumnProperty)])
+    model_attributes = {prop.key for prop in
+                        orm.class_mapper(model.__class__).iterate_properties
+                        if isinstance(prop, orm.ColumnProperty)}
     _changable_attribute_names[class_name] = model_attributes
     return model_attributes