diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 136f8e7a..1c67ab03 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,7 +1,7 @@
 default_language_version:
     python: python3.7
 repos:
--   repo: git://github.com/pre-commit/pre-commit-hooks
+-   repo: https://github.com/pre-commit/pre-commit-hooks
     rev: c8bad492e1b1d65d9126dba3fe3bd49a5a52b9d6  # v2.1.0
     hooks:
     -   id: check-merge-conflict
@@ -11,15 +11,15 @@ repos:
         exclude: ^docs/.*$
     -   id: trailing-whitespace
         exclude: README.md
--   repo: git://github.com/PyCQA/flake8
+-   repo: https://github.com/PyCQA/flake8
     rev: 88caf5ac484f5c09aedc02167c59c66ff0af0068  # 3.7.7
     hooks:
     -   id: flake8
--   repo: git://github.com/asottile/seed-isort-config
+-   repo: https://github.com/asottile/seed-isort-config
     rev: v1.7.0
     hooks:
     -   id: seed-isort-config
--   repo: git://github.com/pre-commit/mirrors-isort
+-   repo: https://github.com/pre-commit/mirrors-isort
     rev: v4.3.4
     hooks:
     -   id: isort
diff --git a/graphene_sqlalchemy/tests/test_types.py b/graphene_sqlalchemy/tests/test_types.py
index 32f01509..1f15fa1a 100644
--- a/graphene_sqlalchemy/tests/test_types.py
+++ b/graphene_sqlalchemy/tests/test_types.py
@@ -1,11 +1,14 @@
 from unittest import mock
 
 import pytest
+import sqlalchemy.exc
+import sqlalchemy.orm.exc
 
 from graphene import (Dynamic, Field, GlobalID, Int, List, Node, NonNull,
                       ObjectType, Schema, String)
 from graphene.relay import Connection
 
+from .. import utils
 from ..converter import convert_sqlalchemy_composite
 from ..fields import (SQLAlchemyConnectionField,
                       UnsortedSQLAlchemyConnectionField, createConnectionField,
@@ -492,3 +495,65 @@ class Meta:
 def test_deprecated_createConnectionField():
     with pytest.warns(DeprecationWarning):
         createConnectionField(None)
+
+
+@mock.patch(utils.__name__ + '.class_mapper')
+def test_unique_errors_propagate(class_mapper_mock):
+    # Define unique error to detect
+    class UniqueError(Exception):
+        pass
+
+    # Mock class_mapper effect
+    class_mapper_mock.side_effect = UniqueError
+
+    # Make sure that errors are propagated from class_mapper when instantiating new classes
+    error = None
+    try:
+        class ArticleOne(SQLAlchemyObjectType):
+            class Meta(object):
+                model = Article
+    except UniqueError as e:
+        error = e
+
+    # Check that an error occured, and that it was the unique error we gave
+    assert error is not None
+    assert isinstance(error, UniqueError)
+
+
+@mock.patch(utils.__name__ + '.class_mapper')
+def test_argument_errors_propagate(class_mapper_mock):
+    # Mock class_mapper effect
+    class_mapper_mock.side_effect = sqlalchemy.exc.ArgumentError
+
+    # Make sure that errors are propagated from class_mapper when instantiating new classes
+    error = None
+    try:
+        class ArticleTwo(SQLAlchemyObjectType):
+            class Meta(object):
+                model = Article
+    except sqlalchemy.exc.ArgumentError as e:
+        error = e
+
+    # Check that an error occured, and that it was the unique error we gave
+    assert error is not None
+    assert isinstance(error, sqlalchemy.exc.ArgumentError)
+
+
+@mock.patch(utils.__name__ + '.class_mapper')
+def test_unmapped_errors_reformat(class_mapper_mock):
+    # Mock class_mapper effect
+    class_mapper_mock.side_effect = sqlalchemy.orm.exc.UnmappedClassError(object)
+
+    # Make sure that errors are propagated from class_mapper when instantiating new classes
+    error = None
+    try:
+        class ArticleThree(SQLAlchemyObjectType):
+            class Meta(object):
+                model = Article
+    except ValueError as e:
+        error = e
+
+    # Check that an error occured, and that it was the unique error we gave
+    assert error is not None
+    assert isinstance(error, ValueError)
+    assert "You need to pass a valid SQLAlchemy Model" in str(error)
diff --git a/graphene_sqlalchemy/types.py b/graphene_sqlalchemy/types.py
index 72f06c06..ac69b697 100644
--- a/graphene_sqlalchemy/types.py
+++ b/graphene_sqlalchemy/types.py
@@ -207,9 +207,11 @@ def __init_subclass_with_meta__(
         _meta=None,
         **options
     ):
-        assert is_mapped_class(model), (
-            "You need to pass a valid SQLAlchemy Model in " '{}.Meta, received "{}".'
-        ).format(cls.__name__, model)
+        # Make sure model is a valid SQLAlchemy model
+        if not is_mapped_class(model):
+            raise ValueError(
+                "You need to pass a valid SQLAlchemy Model in " '{}.Meta, received "{}".'.format(cls.__name__, model)
+            )
 
         if not registry:
             registry = get_global_registry()
diff --git a/graphene_sqlalchemy/utils.py b/graphene_sqlalchemy/utils.py
index b30c0eb4..340ad47e 100644
--- a/graphene_sqlalchemy/utils.py
+++ b/graphene_sqlalchemy/utils.py
@@ -27,7 +27,13 @@ def get_query(model, context):
 def is_mapped_class(cls):
     try:
         class_mapper(cls)
-    except (ArgumentError, UnmappedClassError):
+    except ArgumentError as error:
+        # Only handle ArgumentErrors for non-class objects
+        if "Class object expected" in str(error):
+            return False
+        raise
+    except UnmappedClassError:
+        # Unmapped classes return false
         return False
     else:
         return True