diff --git a/tests/webtbs/tw13628b.pp b/tests/webtbs/tw13628b.pp
index c64f6640c2..a46d9caeee 100644
--- a/tests/webtbs/tw13628b.pp
+++ b/tests/webtbs/tw13628b.pp
@@ -13,9 +13,17 @@ const
   {$endif unix}
 
   {$ifdef windows}
-  libname = 'tw13628a.dll';
+   {$DEFINE NODLLPREFIX}
   {$endif windows}
 
+  {$ifdef os2}
+   {$DEFINE NODLLPREFIX}
+  {$endif os2}
+
+  {$IFDEF NODLLPREFIX}
+  libname = 'tw13628a.' + SharedSuffix;
+  {$ENDIF NODLLPREFIX}
+
 var
   hdl: TLibHandle;
 begin