diff --git a/.github/workflows/examples-ci.yml b/.github/workflows/examples-ci.yml
index 310e6f1..23adbcc 100644
--- a/.github/workflows/examples-ci.yml
+++ b/.github/workflows/examples-ci.yml
@@ -249,7 +249,7 @@ jobs:
         # from PyPI, which is what makes them a check on the release.
         run: |
           python -m pip install --require-hashes -r ../requirements/wcm-harness.txt
-          python -m pip install "weight-custody-manifest[model-signing]>=0.27.0"
+          python -m pip install -r requirements-model-signing.txt
 
       - name: Run every offline demo and the unit tests
         run: python run_demos.py
diff --git a/examples/weight-custody-manifest/README.md b/examples/weight-custody-manifest/README.md
index 05e87a4..7ed353c 100644
--- a/examples/weight-custody-manifest/README.md
+++ b/examples/weight-custody-manifest/README.md
@@ -67,7 +67,7 @@ The same machinery, two trust settings. **Closed** weights (a frontier model dep
 
 - **`transparency_log.py`** -- the append-only Merkle log (SPEC 3.7 / RFC 9162): inclusion and consistency proofs, and a monitor detecting a suppressed revocation.
 - **`post_quantum.py`** -- sign and verify a manifest with ML-DSA-65 and with the Ed25519+ML-DSA-65 hybrid profile.
-- **`provenance_model_signing.py`** -- interop with OpenSSF model-signing: a WCM manifest references a model-signing signature as its provenance, and `verify_provenance` cryptographically verifies it. Needs the extra: `pip install "weight-custody-manifest[model-signing]"`.
+- **`provenance_model_signing.py`** -- interop with OpenSSF model-signing: a WCM manifest references a model-signing signature as its provenance, and `verify_provenance` cryptographically verifies it. Install `requirements-model-signing.txt` for this demo.
 
 ### Verifying real attestations
 
@@ -81,7 +81,7 @@ The same machinery, two trust settings. **Closed** weights (a frontier model dep
 
 ```bash
 python closed_model_e2e.py                             # any of the offline examples
-pip install "weight-custody-manifest[model-signing]"   # for provenance_model_signing.py
+pip install -r requirements-model-signing.txt          # for provenance_model_signing.py
 pip install -r requirements-infer.txt                  # for real_open_model.py
 python real_open_model.py
 ```
diff --git a/examples/weight-custody-manifest/provenance_model_signing.py b/examples/weight-custody-manifest/provenance_model_signing.py
index 7518c74..97bcd12 100644
--- a/examples/weight-custody-manifest/provenance_model_signing.py
+++ b/examples/weight-custody-manifest/provenance_model_signing.py
@@ -1,6 +1,6 @@
 """Provenance interop: WCM custody on top of an OpenSSF model-signing signature.
 
-    pip install "weight-custody-manifest[model-signing]"
+    pip install -r requirements-model-signing.txt
     python provenance_model_signing.py
 
 Real WCM code, no hardware. OpenSSF model-signing (Sigstore) answers "who signed
diff --git a/examples/weight-custody-manifest/requirements-lora.txt b/examples/weight-custody-manifest/requirements-lora.txt
index ed115d0..72f9a9c 100644
--- a/examples/weight-custody-manifest/requirements-lora.txt
+++ b/examples/weight-custody-manifest/requirements-lora.txt
@@ -1,3 +1,5 @@
+# Include WCM and the model-signing dependency setup used by the offline demo.
+-r requirements-model-signing.txt
 huggingface_hub==1.33.0
 safetensors==0.8.0
 transformers==5.19.0
diff --git a/examples/weight-custody-manifest/requirements-model-signing.txt b/examples/weight-custody-manifest/requirements-model-signing.txt
new file mode 100644
index 0000000..a6eff8e
--- /dev/null
+++ b/examples/weight-custody-manifest/requirements-model-signing.txt
@@ -0,0 +1,7 @@
+-r requirements.txt
+weight-custody-manifest[model-signing]>=0.32.0
+
+# model-signing 1.1.1 imports OpenSSL.crypto without declaring pyOpenSSL.
+# sigstore 4.5.1 no longer brings it in transitively. Version 26.4.0 is the
+# first pyOpenSSL release compatible with WCM's cryptography 50 requirement.
+pyOpenSSL>=26.4.0,<27
diff --git a/examples/weight-custody-manifest/requirements.txt b/examples/weight-custody-manifest/requirements.txt
index ee29129..a4c45ec 100644
--- a/examples/weight-custody-manifest/requirements.txt
+++ b/examples/weight-custody-manifest/requirements.txt
@@ -1,4 +1,4 @@
 # The Weight Custody Manifest reference SDK, from PyPI.
-# Covers the offline examples. provenance_model_signing.py additionally needs the
-# [model-signing] extra: pip install "weight-custody-manifest[model-signing]".
+# Covers the offline examples. For provenance_model_signing.py, install
+# requirements-model-signing.txt instead.
 weight-custody-manifest>=0.32.0