diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
index f5cb85bc1bf30..530ff90c4cd16 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
@@ -29,6 +29,7 @@
 #  include "sanitizer_solaris.h"
 
 #  if SANITIZER_HAIKU
+#    define _GNU_SOURCE
 #    define _DEFAULT_SOURCE
 #  endif