diff --git a/pywidevine/cdm.py b/pywidevine/cdm.py
index 1b891a1..be14a36 100644
--- a/pywidevine/cdm.py
+++ b/pywidevine/cdm.py
@@ -424,7 +424,7 @@ class Cdm:
     @staticmethod
     def encrypt_client_id(
         client_id: ClientIdentification,
-        service_certificate: DrmCertificate,
+        service_certificate: Union[SignedMessage, SignedDrmCertificate, DrmCertificate],
         key: bytes = None,
         iv: bytes = None
     ) -> EncryptedClientIdentification:
@@ -432,6 +432,14 @@ class Cdm:
         privacy_key = key or get_random_bytes(16)
         privacy_iv = iv or get_random_bytes(16)
 
+        if isinstance(service_certificate, SignedMessage):
+            signed_drm_certificate = SignedDrmCertificate()
+            signed_drm_certificate.ParseFromString(service_certificate.msg)
+            service_certificate = signed_drm_certificate
+        if isinstance(service_certificate, SignedDrmCertificate):
+            drm_certificate = DrmCertificate()
+            drm_certificate.ParseFromString(service_certificate.drm_certificate)
+            service_certificate = drm_certificate
         if not isinstance(service_certificate, DrmCertificate):
             raise ValueError(f"Expecting Service Certificate to be a DrmCertificate, not {service_certificate!r}")