diff --git a/doc/mach.texi b/doc/mach.texi
index 2c22fa38..fdc36d45 100644
--- a/doc/mach.texi
+++ b/doc/mach.texi
@@ -4830,11 +4830,11 @@ argument set to @code{THREAD_EXCEPTION_PORT}.
 @node Exceptions
 @subsection Exceptions
 
-@deftypefun kern_return_t catch_exception_raise (@w{mach_port_t @var{exception_port}}, @w{thread_t @var{thread}}, @w{task_t @var{task}}, @w{int @var{exception}}, @w{int @var{code}}, @w{int @var{subcode}})
+@deftypefun kern_return_t catch_exception_raise (@w{mach_port_t @var{exception_port}}, @w{thread_t @var{thread}}, @w{task_t @var{task}}, @w{int @var{exception}}, @w{int @var{code}}, @w{long @var{subcode}})
 XXX Fixme
 @end deftypefun
 
-@deftypefun kern_return_t exception_raise (@w{mach_port_t @var{exception_port}}, @w{mach_port_t @var{thread}}, @w{mach_port_t @var{task}}, @w{integer_t @var{exception}}, @w{integer_t @var{code}}, @w{integer_t @var{subcode}})
+@deftypefun kern_return_t exception_raise (@w{mach_port_t @var{exception_port}}, @w{mach_port_t @var{thread}}, @w{mach_port_t @var{task}}, @w{integer_t @var{exception}}, @w{integer_t @var{code}}, @w{long_integer_t @var{subcode}})
 XXX Fixme
 @end deftypefun
 
diff --git a/i386/i386/trap.c b/i386/i386/trap.c
index 34ccb6a5..f7bd8e38 100644
--- a/i386/i386/trap.c
+++ b/i386/i386/trap.c
@@ -628,7 +628,7 @@ void
 i386_exception(
 	int	exc,
 	int	code,
-	int	subcode)
+	long	subcode)
 {
 	spl_t	s;
 
diff --git a/i386/i386/trap.h b/i386/i386/trap.h
index d9df7afa..e82164d0 100644
--- a/i386/i386/trap.h
+++ b/i386/i386/trap.h
@@ -40,7 +40,7 @@ void
 i386_exception(
 	int	exc,
 	int	code,
-	int	subcode) __attribute__ ((noreturn));
+	long	subcode) __attribute__ ((noreturn));
 
 extern void
 thread_kdb_return(void);
diff --git a/include/mach/exc.defs b/include/mach/exc.defs
index 94af828c..28638e2f 100644
--- a/include/mach/exc.defs
+++ b/include/mach/exc.defs
@@ -44,4 +44,4 @@ routine		exception_raise(
 			task		: mach_port_t;
 			exception	: integer_t;
 			code		: integer_t;
-			subcode		: integer_t);
+			subcode		: rpc_long_integer_t);
diff --git a/kern/exception.c b/kern/exception.c
index 1014b3ed..10435b5c 100644
--- a/kern/exception.c
+++ b/kern/exception.c
@@ -85,9 +85,9 @@ boolean_t debug_user_with_kdb = FALSE;
 
 void
 exception(
-	integer_t _exception, 
-	integer_t code, 
-	integer_t subcode)
+	integer_t _exception,
+	integer_t code,
+	long_integer_t subcode)
 {
 	ipc_thread_t self = current_thread();
 	ipc_port_t exc_port;
@@ -157,9 +157,9 @@ exception(
 
 void
 exception_try_task(
-	integer_t _exception, 
-	integer_t code, 
-	integer_t subcode)
+	integer_t _exception,
+	integer_t code,
+	long_integer_t subcode)
 {
 	ipc_thread_t self = current_thread();
 	task_t task = self->task;
@@ -277,11 +277,17 @@ struct mach_exception {
 	mach_msg_type_t		codeType;
 	integer_t		code;
 	mach_msg_type_t		subcodeType;
-	integer_t		subcode;
+	rpc_long_integer_t	subcode;
 };
 
 #define	INTEGER_T_SIZE_IN_BITS	(8 * sizeof(integer_t))
 #define	INTEGER_T_TYPE		MACH_MSG_TYPE_INTEGER_T
+#define RPC_LONG_INTEGER_T_SIZE_IN_BITS	(8 * sizeof(rpc_long_integer_t))
+#if defined(__x86_64__) && !defined(USER32)
+#define RPC_LONG_INTEGER_T_TYPE	MACH_MSG_TYPE_INTEGER_64
+#else
+#define RPC_LONG_INTEGER_T_TYPE	MACH_MSG_TYPE_INTEGER_32
+#endif
 					/* in mach/machine/vm_types.h */
 
 mach_msg_type_t exc_port_proto = {
@@ -304,6 +310,16 @@ mach_msg_type_t exc_code_proto = {
 	/* msgt_unused = */		0
 };
 
+mach_msg_type_t exc_subcode_proto = {
+	/* msgt_name = */		RPC_LONG_INTEGER_T_TYPE,
+	/* msgt_size = */		RPC_LONG_INTEGER_T_SIZE_IN_BITS,
+	/* msgt_number = */		1,
+	/* msgt_inline = */		TRUE,
+	/* msgt_longform = */		FALSE,
+	/* msgt_deallocate = */		FALSE,
+	/* msgt_unused = */		0
+};
+
 /*
  *	Routine:	exception_raise
  *	Purpose:
@@ -329,9 +345,9 @@ exception_raise(
 	ipc_port_t 	dest_port,
 	ipc_port_t 	thread_port,
 	ipc_port_t 	task_port,
-	integer_t 	_exception, 
-	integer_t 	code, 
-	integer_t 	subcode)
+	integer_t 	_exception,
+	integer_t 	code,
+	long_integer_t 	subcode)
 {
 	ipc_thread_t self = current_thread();
 	ipc_thread_t receiver;
@@ -521,7 +537,7 @@ exception_raise(
 	exc->exception = _exception;
 	exc->codeType = exc_code_proto;
 	exc->code = code;
-	exc->subcodeType = exc_code_proto;
+	exc->subcodeType = exc_subcode_proto;
 	exc->subcode = subcode;
 
 	/*
@@ -725,7 +741,7 @@ exception_raise(
 	exc->exception = _exception;
 	exc->codeType = exc_code_proto;
 	exc->code = code;
-	exc->subcodeType = exc_code_proto;
+	exc->subcodeType = exc_subcode_proto;
 	exc->subcode = subcode;
 
 	ipc_mqueue_send_always(kmsg);
diff --git a/kern/exception.h b/kern/exception.h
index 55902dd1..36138da8 100644
--- a/kern/exception.h
+++ b/kern/exception.h
@@ -26,13 +26,13 @@ extern void
 exception(
 	integer_t 	_exception,
 	integer_t	code,
-	integer_t	subcode) __attribute__ ((noreturn));
+	long_integer_t	subcode) __attribute__ ((noreturn));
 
 extern void
 exception_try_task(
 	integer_t 	_exception,
 	integer_t	code,
-	integer_t	subcode) __attribute__ ((noreturn));
+	long_integer_t	subcode) __attribute__ ((noreturn));
 
 extern void
 exception_no_server(void) __attribute__ ((noreturn));
@@ -44,7 +44,7 @@ exception_raise(
 	ipc_port_t task_port,
 	integer_t  _exception,
 	integer_t  code,
-	integer_t  subcode) __attribute__ ((noreturn));
+	long_integer_t  subcode) __attribute__ ((noreturn));
 
 extern kern_return_t
 exception_parse_reply(ipc_kmsg_t kmsg);
diff --git a/kern/thread.h b/kern/thread.h
index f8989f45..3485f6af 100644
--- a/kern/thread.h
+++ b/kern/thread.h
@@ -190,7 +190,7 @@ struct thread {
 			struct ipc_port *port;
 			int exc;
 			int code;
-			int subcode;
+			long subcode;
 		} exception;
 		void *other;		/* catch-all for other state */
 	} saved;