diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index ca5e7b91a95..6287b2b9dff 100644
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,7 @@
+2018-09-05  Hans-Peter Nilsson  <hp@axis.com>
+
+	* io/async.h: Use __gthread_mutex_t, not pthread_mutex_t.
+
 2018-09-01  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	* io/io.h: Change declaration of vlist type to
diff --git a/libgfortran/io/async.h b/libgfortran/io/async.h
index 4ddb498069c..c747bc5aa7b 100644
--- a/libgfortran/io/async.h
+++ b/libgfortran/io/async.h
@@ -337,8 +337,8 @@ struct adv_cond
 
 typedef struct async_unit
 {
-  pthread_mutex_t io_lock;   /* Lock for doing actual I/O. */
-  pthread_mutex_t lock;      /* Lock for manipulating the queue structure.  */
+  __gthread_mutex_t io_lock;   /* Lock for doing actual I/O. */
+  __gthread_mutex_t lock;      /* Lock for manipulating the queue structure.  */
   bool empty;
   struct
   {