diff --git a/setup.py b/setup.py
index 3264329..05e639c 100644
--- a/setup.py
+++ b/setup.py
@@ -24,7 +24,10 @@
     packages=['spanner_orm', 'spanner_orm.admin'],
     include_package_data=True,
     python_requires='~=3.7',
-    install_requires=['google-cloud-spanner >= 1.6, <2.0.0dev', 'frozendict'],
+    install_requires=[
+        'google-cloud-spanner >= 1.6, <2.0.0dev',
+        'immutabledict',
+    ],
     tests_require=['absl-py', 'google-api-core', 'portpicker'],
     entry_points={
         'console_scripts': ['spanner-orm = spanner_orm.admin.scripts:main']
diff --git a/spanner_orm/condition.py b/spanner_orm/condition.py
index 5694f70..fc0cede 100644
--- a/spanner_orm/condition.py
+++ b/spanner_orm/condition.py
@@ -29,9 +29,9 @@
 from spanner_orm import index
 from spanner_orm import relationship
 
-import frozendict
 from google.api_core import datetime_helpers
 from google.cloud.spanner_v1.proto import type_pb2
+import immutabledict
 
 T = TypeVar('T')
 
@@ -254,7 +254,7 @@ class ArbitraryCondition(Condition):
   def __init__(
       self,
       sql_template: str,
-      substitutions: Mapping[str, Substitution] = frozendict.frozendict(),
+      substitutions: Mapping[str, Substitution] = immutabledict.immutabledict(),
       *,
       segment: Segment,
   ):