diff --git a/native/doscalls.c b/native/doscalls.c
index 2400a40..1966d42 100644
--- a/native/doscalls.c
+++ b/native/doscalls.c
@@ -411,13 +411,14 @@ APIRET DosSetExceptionHandler(PEXCEPTIONREGISTRATIONRECORD rec)
     return NO_ERROR;
 } // DosSetExceptionHandler
 
-ULONG DosFlatToSel(void)
+ULONG DosFlatToSel(PVOID ptr)
 {
     // this actually passes the arg in eax instead of the stack.
-    uint32 eax = 0;
-    __asm__ __volatile__ ("" : "=a" (eax));
-    TRACE_NATIVE("DosFlatToSel(%p)", (void *) (size_t) eax);
-    return (ULONG) 0x12345678;  // !!! FIXME
+    //uint32 eax = 0;
+    //__asm__ __volatile__ ("" : "=a" (eax));
+    //TRACE_NATIVE("DosFlatToSel(%p)", (void *) (size_t) eax);
+    TRACE_NATIVE("DosFlatToSel(%p)", ptr);
+    return ((ULONG) ((size_t)ptr)) >> 16;  // !!! FIXME
 } // DosFlatToSel
 
 APIRET DosSetSignalExceptionFocus(BOOL32 flag, PULONG pulTimes)
diff --git a/native/doscalls.h b/native/doscalls.h
index 2aeda45..b016bb6 100644
--- a/native/doscalls.h
+++ b/native/doscalls.h
@@ -181,7 +181,7 @@ APIRET OS2API DosExitList(ULONG ordercode, PFNEXITLIST pfn);
 APIRET OS2API DosCreateEventSem(PSZ pszName, PHEV phev, ULONG flAttr, BOOL32 fState);
 APIRET OS2API DosCreateMutexSem(PSZ pszName, PHMTX phmtx, ULONG flAttr, BOOL32 fState);
 APIRET OS2API DosSetExceptionHandler(PEXCEPTIONREGISTRATIONRECORD pERegRec);
-ULONG OS2API DosFlatToSel(void);
+ULONG OS2API DosFlatToSel(PVOID ptr);
 APIRET OS2API DosSetSignalExceptionFocus(BOOL32 flag, PULONG pulTimes);
 APIRET OS2API DosSetRelMaxFH(PLONG pcbReqCount, PULONG pcbCurMaxFH);
 APIRET OS2API DosAllocMem(PPVOID ppb, ULONG cb, ULONG flag);