diff --git a/sigstore/_internal/fulcio/__init__.py b/sigstore/_internal/fulcio/__init__.py
index 57162df9..8a6ceec3 100644
--- a/sigstore/_internal/fulcio/__init__.py
+++ b/sigstore/_internal/fulcio/__init__.py
@@ -17,7 +17,7 @@
 """
 
 
-from ._client import (
+from .client import (
     FulcioCertificateSigningRequest,
     FulcioCertificateSigningResponse,
     FulcioClient,
diff --git a/sigstore/_internal/fulcio/_client.py b/sigstore/_internal/fulcio/client.py
similarity index 100%
rename from sigstore/_internal/fulcio/_client.py
rename to sigstore/_internal/fulcio/client.py
diff --git a/sigstore/_internal/rekor/__init__.py b/sigstore/_internal/rekor/__init__.py
index 50ef344e..e04f5732 100644
--- a/sigstore/_internal/rekor/__init__.py
+++ b/sigstore/_internal/rekor/__init__.py
@@ -16,6 +16,6 @@
 APIs for interacting with Rekor.
 """
 
-from ._client import RekorClient, RekorEntry, RekorInclusionProof
+from .client import RekorClient, RekorEntry, RekorInclusionProof
 
 __all__ = ["RekorClient", "RekorEntry", "RekorInclusionProof"]
diff --git a/sigstore/_internal/rekor/_client.py b/sigstore/_internal/rekor/client.py
similarity index 97%
rename from sigstore/_internal/rekor/_client.py
rename to sigstore/_internal/rekor/client.py
index 55ee48dd..1c7c3563 100644
--- a/sigstore/_internal/rekor/_client.py
+++ b/sigstore/_internal/rekor/client.py
@@ -66,6 +66,9 @@ class RekorInclusionProof(BaseModel):
     tree_size: int = Field(..., alias="treeSize")
     hashes: List[str] = Field(..., alias="hashes")
 
+    class Config:
+        allow_population_by_field_name = True
+
     @validator("log_index")
     def log_index_positive(cls, v: int) -> int:
         if v < 0:
@@ -82,7 +85,7 @@ def tree_size_positive(cls, v: int) -> int:
     def log_index_within_tree_size(
         cls, v: int, values: Dict[str, Any], **kwargs: Any
     ) -> int:
-        if v <= values["log_index"]:
+        if "log_index" in values and v <= values["log_index"]:
             raise ValueError(
                 "Inclusion proof has log index greater than or equal to tree size: "
                 f"{v} <= {values['log_index']}"
diff --git a/test/internal/rekor/__init__.py b/test/internal/rekor/__init__.py
new file mode 100644
index 00000000..88cb71fa
--- /dev/null
+++ b/test/internal/rekor/__init__.py
@@ -0,0 +1,13 @@
+# Copyright 2022 The Sigstore Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
diff --git a/test/internal/rekor/test_client.py b/test/internal/rekor/test_client.py
new file mode 100644
index 00000000..95b13e7e
--- /dev/null
+++ b/test/internal/rekor/test_client.py
@@ -0,0 +1,51 @@
+# Copyright 2022 The Sigstore Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+from pydantic import ValidationError
+
+from sigstore._internal.rekor import client
+
+
+class TestRekorInclusionProof:
+    def test_valid(self):
+        proof = client.RekorInclusionProof(
+            log_index=1, root_hash="abcd", tree_size=2, hashes=[]
+        )
+        assert proof is not None
+
+    def test_negative_log_index(self):
+        with pytest.raises(
+            ValidationError, match="Inclusion proof has invalid log index"
+        ):
+            client.RekorInclusionProof(
+                log_index=-1, root_hash="abcd", tree_size=2, hashes=[]
+            )
+
+    def test_negative_tree_size(self):
+        with pytest.raises(
+            ValidationError, match="Inclusion proof has invalid tree size"
+        ):
+            client.RekorInclusionProof(
+                log_index=1, root_hash="abcd", tree_size=-1, hashes=[]
+            )
+
+    def test_log_index_outside_tree_size(self):
+        with pytest.raises(
+            ValidationError,
+            match="Inclusion proof has log index greater than or equal to tree size",
+        ):
+            client.RekorInclusionProof(
+                log_index=2, root_hash="abcd", tree_size=1, hashes=[]
+            )