Index: modcargo-crates/aws-lc-sys-0.27.0/aws-lc/crypto/fipsmodule/bcm.c
--- modcargo-crates/aws-lc-sys-0.27.0/aws-lc/crypto/fipsmodule/bcm.c.orig
+++ modcargo-crates/aws-lc-sys-0.27.0/aws-lc/crypto/fipsmodule/bcm.c
@@ -15,6 +15,9 @@
 #if !defined(_GNU_SOURCE)
 #define _GNU_SOURCE  // needed for syscall() on Linux.
 #endif
+#if !defined(_BSD_SOURCE)
+#define _BSD_SOURCE  // needed for arc4random_buf() and bsd-style u_foo types
+#endif
 
 #include <openssl/crypto.h>
 
