diff --git a/libwvdrmengine/oemcrypto/test/oemcrypto_cast_test.h b/libwvdrmengine/oemcrypto/test/oemcrypto_cast_test.h
index 0efc8ee3..9aa464bd 100644
--- a/libwvdrmengine/oemcrypto/test/oemcrypto_cast_test.h
+++ b/libwvdrmengine/oemcrypto/test/oemcrypto_cast_test.h
@@ -29,7 +29,7 @@ class OEMCryptoLoadsCertificateAlternates : public OEMCryptoLoadsCertificate {
   // The message to be signed by OEMCrypto_GenerateRSASignature() starts with a
   // constant digest info prefix followed by a SHA-1 hash of the message.
   void PrepareCastDigestedMessage(const std::vector<uint8_t>& message,
-                                  std::vector<uint8_t>& digested_message) {
+                                  std::vector<uint8_t>& digest) {
     // The application will compute the SHA-1 Hash of the message, so this
     // test must do that also.
     uint8_t hash[SHA_DIGEST_LENGTH];
@@ -39,11 +39,10 @@ class OEMCryptoLoadsCertificateAlternates : public OEMCryptoLoadsCertificate {
     }
     // The application will prepend the digest info to the hash.
     // SHA-1 digest info prefix = 0x30 0x21 0x30 ...
-    vector<uint8_t> digest = wvutil::a2b_hex("3021300906052b0e03021a05000414");
-    digested_message.insert(digested_message.end(), digest.begin(),
-                            digest.end());
-    digested_message.insert(digested_message.end(), hash,
-                            hash + SHA_DIGEST_LENGTH);
+    static const std::vector<uint8_t> prefix =
+        wvutil::a2b_hex("3021300906052b0e03021a05000414");
+    digest.insert(digest.end(), prefix.begin(), prefix.end());
+    digest.insert(digest.end(), hash, hash + SHA_DIGEST_LENGTH);
   }
 
   void TestSignature(RSA_Padding_Scheme scheme, size_t size) {