diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f89f745ebf1..0f137217b57 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2016-04-20  Pedro Alves  <palves@redhat.com>
+
+	* darwin-nat.c (darwin_resume_thread): Add uintptr_t cast.
+
 2016-04-20  Doug Evans  <xdje42@gmail.com>
 
 	* symmisc.c (dump_symtab_1): Print owning compunit for identical
diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index 082a056ec11..16294b22612 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -728,7 +728,7 @@ darwin_resume_thread (struct inferior *inf, darwin_thread_t *thread,
 	{
 	  /* Either deliver a new signal or cancel the signal received.  */
 	  res = PTRACE (PT_THUPDATE, inf->pid,
-			(caddr_t)thread->gdb_port, nsignal);
+			(caddr_t) (uintptr_t) thread->gdb_port, nsignal);
 	  if (res < 0)
 	    inferior_debug (1, _("ptrace THUP: res=%d\n"), res);
 	}