diff --git a/libgomp/ChangeLog b/libgomp/ChangeLog
index e0a128f948f..0ead223d83a 100644
--- a/libgomp/ChangeLog
+++ b/libgomp/ChangeLog
@@ -1,3 +1,8 @@
+2019-05-20  Jakub Jelinek  <jakub@redhat.com>
+
+	PR libgomp/90527
+	* alloc.c (_GNU_SOURCE): Define.
+
 2019-05-17  Thomas Schwinge  <thomas@codesourcery.com>
 
 	* acc_prof.h: New file.
diff --git a/libgomp/alloc.c b/libgomp/alloc.c
index 9145e4b94bf..c28e32f961e 100644
--- a/libgomp/alloc.c
+++ b/libgomp/alloc.c
@@ -27,6 +27,7 @@
    places in the OpenMP API do not make any provision for failure, so in
    general we cannot allow memory allocation to fail.  */
 
+#define _GNU_SOURCE
 #include "libgomp.h"
 #include <stdlib.h>