diff --git a/dlls/advapi32/service.c b/dlls/advapi32/service.c
index bee4847..0c37313 100644
--- a/dlls/advapi32/service.c
+++ b/dlls/advapi32/service.c
@@ -2356,6 +2356,10 @@
             SetLastError(ret);
         return FALSE;
     }
+
+    /* Always return the correct needed size on success */
+    *lpcchBuffer = (size / sizeof(WCHAR)) - 1;
+
     return TRUE;
 }
 
diff --git a/dlls/advapi32/tests/service.c b/dlls/advapi32/tests/service.c
index 77fc85a..8fc1af9 100644
--- a/dlls/advapi32/tests/service.c
+++ b/dlls/advapi32/tests/service.c
@@ -527,12 +527,9 @@
        GetLastError() == ERROR_IO_PENDING /* W2K */ ||
        GetLastError() == 0xdeadbeef       /* NT4, XP, Vista */,
        "Expected ERROR_SUCCESS, ERROR_IO_PENDING or 0xdeadbeef, got %d\n", GetLastError());
-    todo_wine
-    {
     ok(displaysize == tempsizeW, "Expected the needed buffersize\n");
     ok(lstrlenW(displaynameW) == displaysize,
        "Expected the buffer to be the length of the string\n") ;
-    }
     ok(tempsize / 2 == tempsizeW,
        "Expected the needed buffersize (in bytes) to be the same for the A and W call\n");