diff --git a/dlls/advapi32/advapi32.spec b/dlls/advapi32/advapi32.spec
index 638cba127dd..732bf04079c 100644
--- a/dlls/advapi32/advapi32.spec
+++ b/dlls/advapi32/advapi32.spec
@@ -144,8 +144,8 @@
 @ stdcall CredGetSessionTypes(long ptr)
 # @ stub CredGetTargetInfoA
 # @ stub CredGetTargetInfoW
-# @ stub CredIsMarshaledCredentialA
-# @ stub CredIsMarshaledCredentialW
+@ stdcall CredIsMarshaledCredentialA(str)
+@ stdcall CredIsMarshaledCredentialW(wstr)
 # @ stub CredIsProtectedA
 # @ stub CredIsProtectedW
 @ stdcall CredMarshalCredentialA(long ptr ptr)
diff --git a/dlls/advapi32/cred.c b/dlls/advapi32/cred.c
index 432eb5c8570..d15feb7beb4 100644
--- a/dlls/advapi32/cred.c
+++ b/dlls/advapi32/cred.c
@@ -2161,3 +2161,69 @@ BOOL WINAPI CredUnmarshalCredentialW( LPCWSTR cred, PCRED_MARSHAL_TYPE type, PVO
     }
     return TRUE;
 }
+
+/******************************************************************************
+ * CredIsMarshaledCredentialW [ADVAPI32.@]
+ *
+ * Check, if the name parameter is a marshaled credential, hash or binary blob
+ *
+ * PARAMS
+ *  name    the name to check
+ *
+ * RETURNS
+ *  TRUE:  the name parameter is a marshaled credential, hash or binary blob
+ *  FALSE: the name is a plain username
+ */
+BOOL WINAPI CredIsMarshaledCredentialW(LPCWSTR name)
+{
+    TRACE("(%s)\n", debugstr_w(name));
+
+    if (name && name[0] == '@' && name[1] == '@' && name[2] > 'A' && name[3])
+    {
+        char hash[CERT_HASH_LENGTH + 2];
+        int len = strlenW(name + 3 );
+        DWORD size;
+
+        if ((name[2] - 'A') == CertCredential && (len == 27) && cred_decode(name + 3, len, hash))
+            return TRUE;
+
+        if (((name[2] - 'A') == UsernameTargetCredential) &&
+            (len >= 9) && cred_decode(name + 3, 6, (char *)&size) && size)
+            return TRUE;
+
+        if ((name[2] - 'A') == BinaryBlobCredential)
+            FIXME("BinaryBlobCredential not checked\n");
+
+        if ((name[2] - 'A') > BinaryBlobCredential)
+            TRACE("unknown type: %d\n", (name[2] - 'A'));
+    }
+
+    SetLastError(ERROR_INVALID_PARAMETER);
+    return FALSE;
+}
+
+/******************************************************************************
+ * CredIsMarshaledCredentialA [ADVAPI32.@]
+ *
+ * See CredIsMarshaledCredentialW
+ *
+ */
+BOOL WINAPI CredIsMarshaledCredentialA(LPCSTR name)
+{
+    LPWSTR nameW = NULL;
+    BOOL res;
+    int len;
+
+    TRACE("(%s)\n", debugstr_a(name));
+
+    if (name)
+    {
+        len = MultiByteToWideChar(CP_ACP, 0, name, -1, NULL, 0);
+        nameW = HeapAlloc(GetProcessHeap(), 0, len * sizeof(WCHAR));
+        MultiByteToWideChar(CP_ACP, 0, name, -1, nameW, len);
+    }
+
+    res = CredIsMarshaledCredentialW(nameW);
+    HeapFree(GetProcessHeap(), 0, nameW);
+    return res;
+}
diff --git a/include/wincred.h b/include/wincred.h
index fb18a01b97f..d0a75a72bfc 100644
--- a/include/wincred.h
+++ b/include/wincred.h
@@ -248,6 +248,9 @@ WINADVAPI BOOL  WINAPI CredEnumerateW(LPCWSTR,DWORD,DWORD *,PCREDENTIALW **);
 #define                CredEnumerate WINELIB_NAME_AW(CredEnumerate)
 WINADVAPI VOID  WINAPI CredFree(PVOID);
 WINADVAPI BOOL  WINAPI CredGetSessionTypes(DWORD,LPDWORD);
+WINADVAPI BOOL  WINAPI CredIsMarshaledCredentialA(LPCSTR);
+WINADVAPI BOOL  WINAPI CredIsMarshaledCredentialW(LPCWSTR);
+#define                CredIsMarshaledCredential WINELIB_NAME_AW(CredIsMarshaledCredential)
 WINADVAPI BOOL  WINAPI CredMarshalCredentialA(CRED_MARSHAL_TYPE,PVOID,LPSTR *);
 WINADVAPI BOOL  WINAPI CredMarshalCredentialW(CRED_MARSHAL_TYPE,PVOID,LPWSTR *);
 #define                CredMarshalCredential WINELIB_NAME_AW(CredMarshalCredential)