diff --git a/rostests/apitests/ws2_32/WSAStartup.c b/rostests/apitests/ws2_32/WSAStartup.c
index 86d5f421139..5501866eae8 100644
--- a/rostests/apitests/ws2_32/WSAStartup.c
+++ b/rostests/apitests/ws2_32/WSAStartup.c
@@ -78,7 +78,7 @@ CheckStringBuffer(
     EqualLength = RtlCompareMemory(Buffer, Expected, Length);
     if (EqualLength != Length)
     {
-        ok(0, "String is '%S', expected '%S'\n", Buffer, Expected);
+        ok(0, "String is '%s', expected '%s'\n", Buffer, Expected);
         Result = FALSE;
     }