diff --git a/modules/rostests/winetests/winhttp/winhttp.c b/modules/rostests/winetests/winhttp/winhttp.c
index 776ee53e379..7af586d7edf 100644
--- a/modules/rostests/winetests/winhttp/winhttp.c
+++ b/modules/rostests/winetests/winhttp/winhttp.c
@@ -4055,6 +4055,7 @@ static void test_IWinHttpRequest(int port)
 
     hr = IWinHttpRequest_get_ResponseText( req, &response );
     ok( hr == S_OK, "got %08x\n", hr );
+    ok( !memcmp(response, data_start, sizeof(data_start)), "n is '32'\n");
     ok( !memcmp(response, data_start, sizeof(data_start)), "got %s\n", wine_dbgstr_wn(response, 32) );
     SysFreeString( response );
 
@@ -4276,6 +4277,7 @@ static void test_IWinHttpRequest(int port)
 
     hr = IWinHttpRequest_get_ResponseText( req, &response );
     ok( hr == S_OK, "got %08x\n", hr );
+    ok( !memcmp(response, data_start, sizeof(data_start)), "n is '32'\n");
     ok( !memcmp(response, data_start, sizeof(data_start)), "got %s\n", wine_dbgstr_wn(response, 32) );
     SysFreeString( response );
 
diff --git a/sdk/include/reactos/wine/test.h b/sdk/include/reactos/wine/test.h
index 8b9035adfcf..4f590e50f07 100644
--- a/sdk/include/reactos/wine/test.h
+++ b/sdk/include/reactos/wine/test.h
@@ -639,13 +639,14 @@ const char *wine_dbgstr_wn( const WCHAR *str, intptr_t n )
     char *dst, *res;
     size_t size;
 
+    if (!str) return "(null)";
     if (!((ULONG_PTR)str >> 16))
     {
-        if (!str) return "(null)";
         res = get_temp_buffer( 6 );
         sprintf( res, "#%04x", LOWORD(str) );
         return res;
     }
+    if (IsBadStringPtrW(str,n)) return "(invalid)";
     if (n == -1)
     {
         const WCHAR *end = str;