diff --git a/dlls/wintrust/asn.c b/dlls/wintrust/asn.c
index 50923e65137..af7a266091b 100644
--- a/dlls/wintrust/asn.c
+++ b/dlls/wintrust/asn.c
@@ -1720,3 +1720,12 @@ BOOL WINAPI WVTAsn1SpcIndirectDataContentDecode(DWORD dwCertEncodingType,
     TRACE("returning %d\n", ret);
     return ret;
 }
+
+BOOL WINAPI WVTAsn1SpcSpOpusInfoDecode(DWORD dwCertEncodingType,
+ LPCSTR lpszStructType, const BYTE *pbEncoded, DWORD cbEncoded, DWORD dwFlags,
+ void *pvStructInfo, DWORD *pcbStructInfo)
+{
+    FIXME("%p, %d, %08x, %p, %d\n", pbEncoded, cbEncoded, dwFlags,
+     pvStructInfo, *pcbStructInfo);
+    return FALSE;
+}
diff --git a/dlls/wintrust/wintrust.spec b/dlls/wintrust/wintrust.spec
index 078e5bba910..bcac267c85c 100644
--- a/dlls/wintrust/wintrust.spec
+++ b/dlls/wintrust/wintrust.spec
@@ -104,7 +104,7 @@
 @ stub WVTAsn1SpcSigInfoEncode
 @ stub WVTAsn1SpcSpAgencyInfoDecode
 @ stub WVTAsn1SpcSpAgencyInfoEncode
-@ stub WVTAsn1SpcSpOpusInfoDecode
+@ stdcall WVTAsn1SpcSpOpusInfoDecode(long str ptr long long ptr ptr)
 @ stub WVTAsn1SpcSpOpusInfoEncode
 @ stub WVTAsn1SpcStatementTypeDecode
 @ stub WVTAsn1SpcStatementTypeEncode