diff --git a/contrib/libexecinfo/execinfo.h b/contrib/libexecinfo/execinfo.h
index 22460967e83..8a3c36b2da2 100644
--- a/contrib/libexecinfo/execinfo.h
+++ b/contrib/libexecinfo/execinfo.h
@@ -32,6 +32,8 @@
 #ifndef _EXECINFO_H_
 #define _EXECINFO_H_
 
+#include <sys/cdefs.h>
+
 #include <stddef.h>
 
 __BEGIN_DECLS
diff --git a/include/dlfcn.h b/include/dlfcn.h
index 89ec43b332e..9a4ac0faf78 100644
--- a/include/dlfcn.h
+++ b/include/dlfcn.h
@@ -32,6 +32,7 @@
 #ifndef _DLFCN_H_
 #define	_DLFCN_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
 /*
diff --git a/lib/msun/src/math.h b/lib/msun/src/math.h
index be7b8614473..aecc652ea08 100644
--- a/lib/msun/src/math.h
+++ b/lib/msun/src/math.h
@@ -15,6 +15,7 @@
 #ifndef _MATH_H_
 #define	_MATH_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 #include <machine/_limits.h>
 
diff --git a/sys/sys/procdesc.h b/sys/sys/procdesc.h
index 4e8b06fb737..81102dffa6f 100644
--- a/sys/sys/procdesc.h
+++ b/sys/sys/procdesc.h
@@ -108,6 +108,7 @@ int	 procdesc_falloc(struct thread *, struct file **, int *, int,
 
 #else /* !_KERNEL */
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
 #ifndef _PID_T_DECLARED