diff --git a/configure.in b/configure.in
index 6488ee8..69ce67c 100644
--- a/configure.in
+++ b/configure.in
@@ -1227,7 +1227,11 @@ AC_CACHE_CHECK(shift offset of $1, $2,
     if (n==0) {fprintf(stderr,"$1 is 0 (impossible!)\n"); exit(1);}
     i=0; while (!(n&1)) {
        n>>=1; ++i; }
-    fprintf(f, "%u", i);
+    if (3<<i == $1) {
+       fprintf(f, "%u", i);
+    } else {
+       fprintf(f, "-1");	/* anticipate result of xioinitialize assert */
+    }
     exit(0);
  }
  ],
diff --git a/xio-termios.c b/xio-termios.c
index a5c2fd8..4cddaf9 100644
--- a/xio-termios.c
+++ b/xio-termios.c
@@ -43,8 +43,10 @@ const struct optdesc opt_cr2     = { "cr2",     NULL, OPT_CR2,     GROUP_TERMIOS
 #  endif
 #  ifdef CR3
 const struct optdesc opt_cr3     = { "cr3",     NULL, OPT_CR3,     GROUP_TERMIOS, PH_FD, TYPE_CONST, OFUNC_TERMIOS_PATTERN, 1, CR3, CRDLY };
-#endif
+#  endif
+#  if CRDLY_SHIFT >= 0
 const struct optdesc opt_crdly   = { "crdly",   NULL, OPT_CRDLY,   GROUP_TERMIOS, PH_FD, TYPE_UINT,  OFUNC_TERMIOS_VALUE,   1, CRDLY, CRDLY_SHIFT };
+#  endif
 #endif /* defined(CRDLY) */
 #ifdef NLDLY
 #  ifdef NL0
@@ -91,8 +93,10 @@ const struct optdesc opt_tab3    = { "tab3",    NULL, OPT_TAB3,    GROUP_TERMIOS
 #  ifdef XTABS
 const struct optdesc opt_xtabs   = { "xtabs",   NULL, OPT_XTABS,   GROUP_TERMIOS, PH_FD, TYPE_CONST, OFUNC_TERMIOS_FLAG, 1, XTABS, TABDLY };
 #  endif
+#  if TABDLY_SHIFT >= 0
 const struct optdesc opt_tabdly  = { "tabdly",  NULL, OPT_TABDLY,  GROUP_TERMIOS, PH_FD, TYPE_UINT, OFUNC_TERMIOS_VALUE, 1, TABDLY, TABDLY_SHIFT };
-#endif
+#  endif
+#endif /* defined(TABDLY) */
 #ifdef BSDLY
 #  ifdef BS0
 const struct optdesc opt_bs0     = { "bs0",     NULL, OPT_BS0,     GROUP_TERMIOS, PH_FD, TYPE_CONST, OFUNC_TERMIOS_PATTERN, 1, BS0, BSDLY };
@@ -197,7 +201,9 @@ const struct optdesc opt_cs5     = { "cs5",     NULL, OPT_CS5,     GROUP_TERMIOS
 const struct optdesc opt_cs6     = { "cs6",     NULL, OPT_CS6,     GROUP_TERMIOS, PH_FD, TYPE_CONST, OFUNC_TERMIOS_PATTERN, 2, CS6, CSIZE };
 const struct optdesc opt_cs7     = { "cs7",     NULL, OPT_CS7,     GROUP_TERMIOS, PH_FD, TYPE_CONST, OFUNC_TERMIOS_PATTERN, 2, CS7, CSIZE };
 const struct optdesc opt_cs8     = { "cs8",     NULL, OPT_CS8,     GROUP_TERMIOS, PH_FD, TYPE_CONST, OFUNC_TERMIOS_PATTERN, 2, CS8, CSIZE };
+#if CSIZE_SHIFT >= 0
 const struct optdesc opt_csize   = { "csize",   NULL, OPT_CSIZE,   GROUP_TERMIOS, PH_FD, TYPE_UINT,  OFUNC_TERMIOS_VALUE,   2, CSIZE, CSIZE_SHIFT };
+#endif
 const struct optdesc opt_cstopb  = { "cstopb",  NULL, OPT_CSTOPB,  GROUP_TERMIOS, PH_FD, TYPE_BOOL,  OFUNC_TERMIOS_FLAG,    2, CSTOPB };
 const struct optdesc opt_cread   = { "cread",   NULL, OPT_CREAD,   GROUP_TERMIOS, PH_FD, TYPE_BOOL,  OFUNC_TERMIOS_FLAG,    2, CREAD };
 const struct optdesc opt_parenb  = { "parenb",  NULL, OPT_PARENB,  GROUP_TERMIOS, PH_FD, TYPE_BOOL,  OFUNC_TERMIOS_FLAG,    2, PARENB };
diff --git a/xioinitialize.c b/xioinitialize.c
index d04ad71..15d7d64 100644
--- a/xioinitialize.c
+++ b/xioinitialize.c
@@ -37,13 +37,15 @@ int xioinitialize(void) {
 
    /* some assertions about termios */
 #if WITH_TERMIOS
-#ifdef CRDLY
+#if defined(CRDLY) && CRDLY_SHIFT >= 0
    assert(3 << opt_crdly.arg3  == CRDLY);
 #endif
-#ifdef TABDLY
+#if defined(TABDLY) && TABDLY_SHIFT >= 0
    assert(3 << opt_tabdly.arg3 == TABDLY);
 #endif
+#if CSIZE_SHIFT >= 0
    assert(3 << opt_csize.arg3  == CSIZE);
+#endif
    {
       union {
 	 struct termios termarg;
diff --git a/xioopts.c b/xioopts.c
index cc69d65..259bb45 100644
--- a/xioopts.c
+++ b/xioopts.c
@@ -316,7 +316,9 @@ const struct optname optionnames[] = {
 #  ifdef CR3
 	IF_TERMIOS("cr3",	&opt_cr3)
 #  endif
+#  if CRDLY_SHIFT >= 0
 	IF_TERMIOS("crdly",	&opt_crdly)
+#  endif
 #endif /* defined(CRDLY) */
 	IF_TERMIOS("cread",	&opt_cread)
 	IF_OPEN   ("creat",	&opt_o_create)
@@ -332,7 +334,9 @@ const struct optname optionnames[] = {
 	IF_TERMIOS("cs6",	&opt_cs6)
 	IF_TERMIOS("cs7",	&opt_cs7)
 	IF_TERMIOS("cs8",	&opt_cs8)
+#if CSIZE_SHIFT >= 0
 	IF_TERMIOS("csize",	&opt_csize)
+#endif
 	IF_TERMIOS("cstopb",	&opt_cstopb)
 	IF_TERMIOS("ctlecho",	&opt_echoctl)
 	IF_TERMIOS("ctty",	&opt_tiocsctty)
@@ -1456,7 +1460,9 @@ const struct optname optionnames[] = {
 #  ifdef TAB3
 	IF_TERMIOS("tab3",	&opt_tab3)
 #  endif
+#  if TABDLY_SHIFT >= 0
 	IF_TERMIOS("tabdly",	&opt_tabdly)
+#  endif
 #endif
 	IF_TERMIOS("tandem",	&opt_ixoff)
 #ifdef TCP_ABORT_THRESHOLD  /* HP_UX */