diff --git a/kern.c b/kern.c
index b2d2da3..7ea5e52 100644
--- a/kern.c
+++ b/kern.c
@@ -136,10 +136,8 @@ int KERN_C_CALL Net_Call_CX(unsigned int ax, unsigned int bx,
  *   int 21h
  *
  * Return convention mirrors Novell wrapper and old kern.asm Net_Call:
- *   if AL != 0, AH is set to 89h in Net_Call_F2_C_Last.out_ax
- *   return AL only
- */
-int KERN_C_CALL Net_Call_F2_C(UI conn, UI function, UI cx, void *req, void *repl)
+int KERN_C_CALL Net_Call_F2_C(UI function, UI req_len, UI repl_len,
+                                void *req, void *repl)
 {
   union REGS inregs;
   union REGS outregs;
@@ -151,10 +149,19 @@ int KERN_C_CALL Net_Call_F2_C(UI conn, UI function, UI cx, void *req, void *repl
   memset(&segregs, 0, sizeof(segregs));
   memset(&Net_Call_C_Last, 0, sizeof(Net_Call_C_Last));
 
+  /*
+   * Official FLAG.EXE wrapper shape:
+   *   AH    = F2h
+   *   AL    = NCP function, e.g. 57h for NCP 87
+   *   CX    = request length
+   *   DX    = reply buffer length
+   *   DS:SI = request buffer
+   *   ES:DI = reply buffer
+   */
   inregs.h.ah = 0xF2;
   inregs.h.al = (uint8)(function & 0xff);
-  inregs.x.dx = conn;
-  inregs.x.cx = cx;
+  inregs.x.cx = req_len;
+  inregs.x.dx = repl_len;
   inregs.x.si = FP_OFF(req);
   inregs.x.di = FP_OFF(repl);
   segregs.ds  = FP_SEG(req);
@@ -191,10 +198,6 @@ int KERN_C_CALL Net_Call_F2_C(UI conn, UI function, UI cx, void *req, void *repl
 }
 
 
-/*
- * Text dump for quick testing.  Later we can expose this through DEBUG.EXE
- * as "debug netcall" or similar.
- */
 void KERN_C_CALL Net_Call_C_Dump(void)
 {
   fprintf(stdout, "NETCALLC in : AX=%04X BX=%04X CX=%04X DX=%04X DS:SI=%04X:%04X ES:DI=%04X:%04X\n",
diff --git a/kern.h b/kern.h
index ed6ca1d..d391b4f 100644
--- a/kern.h
+++ b/kern.h
@@ -16,7 +16,7 @@ extern int   KERN_CALL Net_Call(UI func, void *req, void *repl);
 extern int   KERN_CALL Net_Call_C(UI func, void *req, void *repl);
 extern int   KERN_CALL Net_Call_CX(UI func, UI bx, UI cx, UI dx,
                                   void *req, void *repl);
-extern int   KERN_CALL Net_Call_F2_C(UI conn, UI function, UI cx,
+extern int   KERN_CALL Net_Call_F2_C(UI function, UI req_len, UI repl_len,
                                     void *req, void *repl);
 extern void  KERN_CALL Net_Call_C_Dump(void);
 extern UI    KERN_CALL Net_Call_C_GetDebug(UI idx);
diff --git a/nwtests.c b/nwtests.c
index d994e79..292736f 100644
--- a/nwtests.c
+++ b/nwtests.c
@@ -266,11 +266,11 @@ static int tests_ncpf2_read_one(char *name, UI cx_mode)
   else
     cx = sizeof(repl.data);        /* alternate: reply buffer size */
 
-  fprintf(stdout, "NCPF2DBG name=%s func=57 conn=%u cx=%u mode=%u req.len=%u repl.max=%u\n",
-          name, connid, cx, cx_mode, (UI)(p - req.data), (UI)sizeof(repl.data));
+  fprintf(stdout, "NCPF2DBG name=%s func=57 conn=%u cx=%u dx=%u mode=%u req.len=%u repl.max=%u\n",
+          name, connid, cx, (UI)sizeof(repl.data), cx_mode, (UI)(p - req.data), (UI)sizeof(repl.data));
   tests_dump_bytes("NCPF2DBG req:", req.data, (p - req.data) > 64 ? 64 : (int)(p - req.data));
 
-  rc = Net_Call_F2_C((UI)connid, 0x57, cx, req.data, repl.data);
+  rc = Net_Call_F2_C(0x57, cx, (UI)sizeof(repl.data), req.data, repl.data);
 
   fprintf(stdout, "NCPF2DBG rc=%04X\n", rc);
   tests_dump_bytes("NCPF2DBG repl:", repl.data, 64);