diff --git a/libwvdrmengine/cdm/core/src/crypto_session.cpp b/libwvdrmengine/cdm/core/src/crypto_session.cpp
index 6cefeaa3..665e9a98 100644
--- a/libwvdrmengine/cdm/core/src/crypto_session.cpp
+++ b/libwvdrmengine/cdm/core/src/crypto_session.cpp
@@ -1539,7 +1539,9 @@ CdmResponseType CryptoSession::LoadOemCertificatePrivateKey(
 // Private.
 CdmResponseType CryptoSession::SelectKey(const std::string& key_id,
                                          CdmCipherMode cipher_mode) {
+  RETURN_IF_NOT_OPEN(CRYPTO_SESSION_NOT_OPEN);
   const OEMCryptoResult sts = WithOecSessionLock("SelectKey", [&] {
+    RETURN_IF_NULL(key_session_, OEMCrypto_ERROR_INVALID_SESSION);
     return key_session_->SelectKey(key_id, cipher_mode);
   });