diff --git a/libbacktrace/ChangeLog b/libbacktrace/ChangeLog
index 5d182e9fc34..3d8d71cfda8 100644
--- a/libbacktrace/ChangeLog
+++ b/libbacktrace/ChangeLog
@@ -1,3 +1,7 @@
+2015-09-17  Ian Lance Taylor  <iant@google.com>
+
+	* posix.c (backtrace_open): Cast second argument of open() to int.
+
 2015-09-11  Ian Lance Taylor  <iant@google.com>
 
 	* Makefile.am (backtrace.lo): Depend on internal.h.
diff --git a/libbacktrace/posix.c b/libbacktrace/posix.c
index 7fa7cd0d5da..f0419a0aa4c 100644
--- a/libbacktrace/posix.c
+++ b/libbacktrace/posix.c
@@ -64,7 +64,7 @@ backtrace_open (const char *filename, backtrace_error_callback error_callback,
   if (does_not_exist != NULL)
     *does_not_exist = 0;
 
-  descriptor = open (filename, O_RDONLY | O_BINARY | O_CLOEXEC);
+  descriptor = open (filename, (int) (O_RDONLY | O_BINARY | O_CLOEXEC));
   if (descriptor < 0)
     {
       if (does_not_exist != NULL && errno == ENOENT)