diff --git a/lib/libc_r/uthread/uthread_wait4.c b/lib/libc_r/uthread/uthread_wait4.c
index 083c230ec88c..da69a4f26b29 100644
--- a/lib/libc_r/uthread/uthread_wait4.c
+++ b/lib/libc_r/uthread/uthread_wait4.c
@@ -31,6 +31,8 @@
  *
  * $FreeBSD$
  */
+#include <sys/types.h>
+
 #include <errno.h>
 #include <sys/wait.h>
 #ifdef _THREAD_SAFE
diff --git a/lib/libkse/thread/thr_wait4.c b/lib/libkse/thread/thr_wait4.c
index 083c230ec88c..da69a4f26b29 100644
--- a/lib/libkse/thread/thr_wait4.c
+++ b/lib/libkse/thread/thr_wait4.c
@@ -31,6 +31,8 @@
  *
  * $FreeBSD$
  */
+#include <sys/types.h>
+
 #include <errno.h>
 #include <sys/wait.h>
 #ifdef _THREAD_SAFE
diff --git a/lib/libpthread/thread/thr_wait4.c b/lib/libpthread/thread/thr_wait4.c
index 083c230ec88c..da69a4f26b29 100644
--- a/lib/libpthread/thread/thr_wait4.c
+++ b/lib/libpthread/thread/thr_wait4.c
@@ -31,6 +31,8 @@
  *
  * $FreeBSD$
  */
+#include <sys/types.h>
+
 #include <errno.h>
 #include <sys/wait.h>
 #ifdef _THREAD_SAFE