diff --git a/libc/include/bits/posix_limits.h b/libc/include/bits/posix_limits.h
index 31016a8..0f17381 100644
--- a/libc/include/bits/posix_limits.h
+++ b/libc/include/bits/posix_limits.h
@@ -29,6 +29,7 @@
 #ifndef _BITS_POSIX_LIMITS_H_
 #define _BITS_POSIX_LIMITS_H_
 
+#include <sys/cdefs.h>
 
 /* Any constant values here other than -1 or 200809L are explicitly specified by POSIX.1-2008. */
 /* Keep it sorted. */
diff --git a/libc/include/bits/pthread_types.h b/libc/include/bits/pthread_types.h
index 6ac1c68..194a49b 100644
--- a/libc/include/bits/pthread_types.h
+++ b/libc/include/bits/pthread_types.h
@@ -29,6 +29,7 @@
 #ifndef _BITS_PTHREAD_TYPES_H_
 #define _BITS_PTHREAD_TYPES_H_
 
+#include <sys/cdefs.h>
 #include <sys/types.h>
 
 typedef long pthread_t;
diff --git a/libc/include/bits/sa_family_t.h b/libc/include/bits/sa_family_t.h
index 51ea51f..98ca27f 100644
--- a/libc/include/bits/sa_family_t.h
+++ b/libc/include/bits/sa_family_t.h
@@ -29,6 +29,8 @@
 #ifndef _BITS_SA_FAMILY_T_H_
 #define _BITS_SA_FAMILY_T_H_
 
+#include <sys/cdefs.h>
+
 typedef unsigned short sa_family_t;
 
 #endif
diff --git a/libc/include/bits/timespec.h b/libc/include/bits/timespec.h
index 046d898..df7a7ce 100644
--- a/libc/include/bits/timespec.h
+++ b/libc/include/bits/timespec.h
@@ -29,6 +29,7 @@
 #ifndef _BITS_TIMESPEC_H_
 #define _BITS_TIMESPEC_H_
 
+#include <sys/cdefs.h>
 #include <sys/types.h>
 
 /*
diff --git a/libc/include/bits/wchar_limits.h b/libc/include/bits/wchar_limits.h
index f779c1a..ffad604 100644
--- a/libc/include/bits/wchar_limits.h
+++ b/libc/include/bits/wchar_limits.h
@@ -29,6 +29,8 @@
 #ifndef _BITS_WCHAR_LIMITS_H_
 #define _BITS_WCHAR_LIMITS_H_
 
+#include <sys/cdefs.h>
+
 /* Both GCC and clang define __WCHAR_MAX__. */
 #define WCHAR_MAX __WCHAR_MAX__