diff --git a/layercake/layercake/dynamodb.py b/layercake/layercake/dynamodb.py
index c543edd..c44d811 100644
--- a/layercake/layercake/dynamodb.py
+++ b/layercake/layercake/dynamodb.py
@@ -313,8 +313,8 @@ class TransactKey:
     pairs: tuple[KeyPair, ...] = ()
 
     def __add__(self, other: SortKey | KeyPair) -> 'TransactKey':
-        if not isinstance(other, SortKey):
-            raise TypeError('Can only add a SortKey to a TransactKey')
+        if not isinstance(other, (SortKey, KeyPair)):
+            raise TypeError('Can only add a SortKey and KeyPair to a TransactKey')
 
         if isinstance(other, SortKey):
             other = KeyPair(self.pk, other)
diff --git a/layercake/pyproject.toml b/layercake/pyproject.toml
index 5ea55fb..80a8ae4 100644
--- a/layercake/pyproject.toml
+++ b/layercake/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "layercake"
-version = "0.3.4"
+version = "0.3.5"
 description = "Packages shared dependencies to optimize deployment and ensure consistency across functions."
 readme = "README.md"
 authors = [
diff --git a/layercake/uv.lock b/layercake/uv.lock
index b6ea58d..e28b77d 100644
--- a/layercake/uv.lock
+++ b/layercake/uv.lock
@@ -589,7 +589,7 @@ wheels = [
 
 [[package]]
 name = "layercake"
-version = "0.3.3"
+version = "0.3.4"
 source = { editable = "." }
 dependencies = [
     { name = "arnparse" },