diff -r 44e5b48998ef Modules/fcntlmodule.c
--- a/Modules/fcntlmodule.c	Sun Nov 11 00:08:45 2012 -0800
+++ b/Modules/fcntlmodule.c	Sun Nov 11 04:23:05 2012 -0800
@@ -97,20 +97,7 @@
 {
 #define IOCTL_BUFSZ 1024
     int fd;
-    /* In PyArg_ParseTuple below, we use the unsigned non-checked 'I'
-       format for the 'code' parameter because Python turns 0x8000000
-       into either a large positive number (PyLong or PyInt on 64-bit
-       platforms) or a negative number on others (32-bit PyInt)
-       whereas the system expects it to be a 32bit bit field value
-       regardless of it being passed as an int or unsigned long on
-       various platforms.  See the termios.TIOCSWINSZ constant across
-       platforms for an example of thise.
-
-       If any of the 64bit platforms ever decide to use more than 32bits
-       in their unsigned long ioctl codes this will break and need
-       special casing based on the platform being built on.
-     */
-    unsigned int code;
+    IOCTL_CODE_TYPE code;
     int arg;
     int ret;
     Py_buffer pstr;
@@ -119,7 +106,7 @@
     int mutate_arg = 1;
     char buf[IOCTL_BUFSZ+1];  /* argument plus NUL byte */
 
-    if (PyArg_ParseTuple(args, "O&Iw*|i:ioctl",
+    if (PyArg_ParseTuple(args, "O&" IOCTL_CODE_FTYPE "w*|i:ioctl",
                          conv_descriptor, &fd, &code,
                          &pstr, &mutate_arg)) {
         char *arg;
@@ -174,7 +161,7 @@
     }
 
     PyErr_Clear();
-    if (PyArg_ParseTuple(args, "O&Is*:ioctl",
+    if (PyArg_ParseTuple(args, "O&" IOCTL_CODE_FTYPE "s*:ioctl",
                          conv_descriptor, &fd, &code, &pstr)) {
         str = pstr.buf;
         len = pstr.len;
@@ -201,8 +188,9 @@
     PyErr_Clear();
     arg = 0;
     if (!PyArg_ParseTuple(args,
-         "O&I|i;ioctl requires a file or file descriptor,"
-         " an integer and optionally an integer or buffer argument",
+         "O&" IOCTL_CODE_FTYPE "|i;ioctl requires a file or file "
+	 "descriptor, an integer and optionally an integer or buffer "
+	 "argument",
                           conv_descriptor, &fd, &code, &arg)) {
       return NULL;
     }
diff -r 44e5b48998ef configure.ac
--- a/configure.ac	Sun Nov 11 00:08:45 2012 -0800
+++ b/configure.ac	Sun Nov 11 04:23:05 2012 -0800
@@ -4612,6 +4612,34 @@
     esac
 fi
 
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Wall -Werror"
+AC_MSG_CHECKING(ioctl code argument type is unsigned long)
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+#include <sys/ioctl.h>
+int main() {
+  typedef int (*ioctl_fn_t)(int, unsigned long, ...);
+  ioctl_fn_t _ioctl = ioctl;
+  return _ioctl(0, 0, 0);
+}
+]])],[ioctl_code_type="unsigned long"])
+CFLAGS="$save_CFLAGS"
+
+if test "$ioctl_code_type" = "unsigned long"; then
+    # Probably *BSD.
+    AC_MSG_RESULT(yes)
+    ioctl_code_ftype="K"
+else
+    # Fall back to "sane" POSIX value.
+    AC_MSG_RESULT(no)
+    ioctl_code_type="int"
+    ioctl_code_ftype="I"
+fi
+AC_DEFINE_UNQUOTED(IOCTL_CODE_TYPE,$ioctl_code_type,
+                   [Type for code argument in fcntl.ioctl])
+AC_DEFINE_UNQUOTED(IOCTL_CODE_FTYPE,"$ioctl_code_ftype",
+                   [Format string qualifier for code argument in fcntl.ioctl])
+
 # generate output files
 AC_CONFIG_FILES(Makefile.pre Modules/Setup.config Misc/python.pc)
 AC_CONFIG_FILES([Modules/ld_so_aix], [chmod +x Modules/ld_so_aix])
diff -r 44e5b48998ef pyconfig.h.in
--- a/pyconfig.h.in	Sun Nov 11 00:08:45 2012 -0800
+++ b/pyconfig.h.in	Sun Nov 11 04:23:05 2012 -0800
@@ -1116,6 +1116,12 @@
 /* Define to 1 if you have the `_getpty' function. */
 #undef HAVE__GETPTY
 
+/* Format string qualifier for code argument in fcntl.ioctl */
+#undef IOCTL_CODE_FTYPE
+
+/* Type for code argument in fcntl.ioctl */
+#undef IOCTL_CODE_TYPE
+
 /* Define if log1p(-0.) is 0. rather than -0. */
 #undef LOG1P_DROPS_ZERO_SIGN