diff --git a/configure.ac b/configure.ac
index 7a49e84f..22900ec0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -652,6 +652,7 @@ case "${host}" in
 	SYM_PREFIX="_"
 	;;
   *-*-freebsd*)
+	JE_APPEND_VS(CPPFLAGS, -D_BSD_SOURCE)
 	abi="elf"
 	AC_DEFINE([JEMALLOC_SYSCTL_VM_OVERCOMMIT], [ ])
 	force_lazy_lock="1"
diff --git a/include/jemalloc/internal/jemalloc_internal_decls.h b/include/jemalloc/internal/jemalloc_internal_decls.h
index 7d212c4e..983027c8 100644
--- a/include/jemalloc/internal/jemalloc_internal_decls.h
+++ b/include/jemalloc/internal/jemalloc_internal_decls.h
@@ -34,6 +34,10 @@
 #  include <pthread.h>
 #  if defined(__FreeBSD__) || defined(__DragonFly__)
 #  include <pthread_np.h>
+#  include <sched.h>
+#  if defined(__FreeBSD__)
+#    define cpu_set_t cpuset_t
+#  endif
 #  endif
 #  include <signal.h>
 #  ifdef JEMALLOC_OS_UNFAIR_LOCK