diff --git a/libm/Android.bp b/libm/Android.bp
index 25c3e8f..23b9d5e 100644
--- a/libm/Android.bp
+++ b/libm/Android.bp
@@ -510,6 +510,7 @@
 
     cflags: [
         "-D__BIONIC_NO_MATH_INLINES",
+        "-D_BSD_SOURCE",
         "-DFLT_EVAL_METHOD=0",
         "-include freebsd-compat.h",
         "-Werror",