diff --git a/src/cashet/_client_base.py b/src/cashet/_client_base.py
index e63b5f2..59e6110 100644
--- a/src/cashet/_client_base.py
+++ b/src/cashet/_client_base.py
@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import os
-from collections.abc import Callable
+from collections.abc import Callable, Mapping
 from datetime import timedelta
 from pathlib import Path
 from typing import Any
@@ -85,6 +85,16 @@ def resolve_status(status: TaskStatus | str | None) -> TaskStatus | None:
     return status
 
 
+def normalize_tag_filters(
+    tags: Mapping[str, str | None] | None,
+) -> dict[str, str | None]:
+    if not tags:
+        return {}
+if not tags:
+    return {}
+return {str(k): str(v) if v is not None else None for k, v in tags.items()}
+
+
 async def load_result(commit: Commit, store: AsyncStore, serializer: Serializer) -> Any:
     if commit.output_ref is None:
         return None
diff --git a/src/cashet/redis_store.py b/src/cashet/redis_store.py
index 3bb0951..0b4d4f5 100644
--- a/src/cashet/redis_store.py
+++ b/src/cashet/redis_store.py
@@ -9,6 +9,7 @@
 
 from redis.exceptions import WatchError
 
+from cashet._client_base import normalize_tag_filters
 from cashet._runner import BlockingAsyncRunner
 from cashet.models import Commit, ObjectRef, StorageTier, TaskDef, TaskStatus
 
@@ -412,6 +413,7 @@ async def list_commits(
         status: TaskStatus | None = None,
         tags: dict[str, str | None] | None = None,
     ) -> list[Commit]:
+        tag_filters = normalize_tag_filters(tags)
         if func_name:
             hashes = await self._redis.zrevrange(_func_key(func_name), 0, -1)
         else:
@@ -424,7 +426,7 @@ async def list_commits(
                 continue
             if status is not None and commit.status != status:
                 continue
-            if tags is not None and not _matches_tags(commit, tags):
+            if tags is not None and not _matches_tags(commit, tag_filters):
                 continue
             commits.append(commit)
             if len(commits) >= limit:
@@ -579,8 +581,11 @@ async def delete_commit(self, hash: str) -> bool:
             return await self._delete_commit(hash)
 
     async def delete_by_tags(self, tags: dict[str, str | None]) -> int:
+        tag_filters = normalize_tag_filters(tags)
+        if not tag_filters:
+            return 0
         set_keys: list[str] = []
-        for key, val in tags.items():
+        for key, val in tag_filters.items():
             set_keys.append(_tag_key(key) if val is None else _tag_value_key(key, val))
         if len(set_keys) == 1:
             hashes = await self._redis.smembers(set_keys[0])
diff --git a/src/cashet/store.py b/src/cashet/store.py
index a80c60a..b433ad8 100644
--- a/src/cashet/store.py
+++ b/src/cashet/store.py
@@ -12,6 +12,7 @@
 from pathlib import Path
 from typing import Any
 
+from cashet._client_base import normalize_tag_filters
 from cashet._runner import BlockingAsyncRunner
 from cashet.models import Commit, ObjectRef, StorageTier, TaskDef, TaskStatus
 
@@ -390,6 +391,7 @@ def list_commits(
         tags: dict[str, str | None] | None = None,
     ) -> list[Commit]:
         conn = self._connect()
+        tag_filters = normalize_tag_filters(tags)
         query = "SELECT * FROM commits WHERE 1=1"
         params: list[Any] = []
         if func_name:
@@ -398,8 +400,8 @@ def list_commits(
         if status:
             query += " AND status = ?"
             params.append(status.value)
-        if tags:
-            for key, val in tags.items():
+        if tag_filters:
+            for key, val in tag_filters.items():
                 if val is None:
                     query += " AND json_extract(tags, ?) IS NOT NULL"
                     params.append(f"$.{key}")
@@ -665,9 +667,13 @@ def delete_commit(self, hash: str) -> bool:
 
     def delete_by_tags(self, tags: dict[str, str | None]) -> int:
         conn = self._connect(immediate=True)
+        tag_filters = normalize_tag_filters(tags)
+        if not tag_filters:
+            conn.execute("ROLLBACK")
+            return 0
         query = "SELECT hash, output_hash, input_refs FROM commits WHERE 1=1"
         params: list[Any] = []
-        for key, val in tags.items():
+        for key, val in tag_filters.items():
             if val is None:
                 query += " AND json_extract(tags, ?) IS NOT NULL"
                 params.append(f"$.{key}")