diff --git a/pyproject.toml b/pyproject.toml
index 01de65c..deeaa19 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "redis-om"
-version = "0.0.7"
+version = "0.0.8"
 description = "A high-level library containing useful Redis abstractions and tools, like an ORM and leaderboard."
 authors = ["Andrew Brookins <andrew.brookins@redis.com>"]
 maintainers = ["Andrew Brookins <andrew.brookins@redis.com>"]
diff --git a/redis_om/model/model.py b/redis_om/model/model.py
index 95de9ac..017f1bb 100644
--- a/redis_om/model/model.py
+++ b/redis_om/model/model.py
@@ -136,29 +136,6 @@ def decode_redis_value(
         return obj.decode(encoding)
 
 
-class ExpressionProtocol(Protocol):
-    op: Operators
-    left: ExpressionOrModelField
-    right: ExpressionOrModelField
-
-    def __invert__(self) -> "Expression":
-        pass
-
-    def __and__(self, other: ExpressionOrModelField):
-        pass
-
-    def __or__(self, other: ExpressionOrModelField):
-        pass
-
-    @property
-    def name(self) -> str:
-        raise NotImplementedError
-
-    @property
-    def tree(self) -> str:
-        raise NotImplementedError
-
-
 @dataclasses.dataclass
 class NegatedExpression:
     """A negated Expression object.
@@ -814,7 +791,7 @@ class FindQuery:
         return query.execute()[0]
 
 
-class PrimaryKeyCreator(Protocol):
+class PrimaryKeyCreator(abc.ABC):
     def create_pk(self, *args, **kwargs) -> str:
         """Create a new primary key"""
 
diff --git a/tox.ini b/tox.ini
index dc841ba..6ec4fbf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 skipsdist = true
-envlist = py38, py39, py310
+envlist = py37, py38, py39, py310
 
 [testenv]
 whitelist_externals = poetry