diff --git a/include/ctype.h b/include/ctype.h
index f0ca79798b79..299b5028ed27 100644
--- a/include/ctype.h
+++ b/include/ctype.h
@@ -79,7 +79,7 @@ int	isrune(int);
 int	isspecial(int);
 #endif
 
-#if __POSIX_VISIBLE >= 200809
+#if __POSIX_VISIBLE >= 200809 || defined(_XLOCALE_H_)
 #include <xlocale/_ctype.h>
 #endif
 __END_DECLS
diff --git a/include/inttypes.h b/include/inttypes.h
index 9aad660eb28d..f702d2c3ca3a 100644
--- a/include/inttypes.h
+++ b/include/inttypes.h
@@ -45,6 +45,9 @@ typedef struct {
 } imaxdiv_t;
 
 __BEGIN_DECLS
+#ifdef _XLOCALE_H_
+#include <xlocale/_inttypes.h>
+#endif
 intmax_t	imaxabs(intmax_t) __pure2;
 imaxdiv_t	imaxdiv(intmax_t, intmax_t) __pure2;
 
diff --git a/include/langinfo.h b/include/langinfo.h
index 42ad832bb486..8c88efccfa29 100644
--- a/include/langinfo.h
+++ b/include/langinfo.h
@@ -131,7 +131,7 @@ typedef	__nl_item	nl_item;
 __BEGIN_DECLS
 char	*nl_langinfo(nl_item);
 
-#if __POSIX_VISIBLE >= 200809
+#if __POSIX_VISIBLE >= 200809 || defined(_XLOCALE_H_)
 #include <xlocale/_langinfo.h>
 #endif
 __END_DECLS
diff --git a/include/monetary.h b/include/monetary.h
index ade6a88b511f..93f82c1cbdeb 100644
--- a/include/monetary.h
+++ b/include/monetary.h
@@ -43,6 +43,9 @@ typedef	__ssize_t	ssize_t;
 #endif
 
 __BEGIN_DECLS
+#ifdef _XLOCALE_H_
+#include <xlocale/_monetary.h>
+#endif
 ssize_t	strfmon(char * __restrict, size_t, const char * __restrict, ...);
 __END_DECLS
 
diff --git a/include/stdio.h b/include/stdio.h
index 02032d9788fd..2fd91259e800 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -225,6 +225,9 @@ __END_DECLS
 #define	stderr	__stderrp
 
 __BEGIN_DECLS
+#ifdef _XLOCALE_H_
+#include <xlocale/_stdio.h>
+#endif
 /*
  * Functions defined in ANSI C standard.
  */
diff --git a/include/stdlib.h b/include/stdlib.h
index 11ac074374dd..7aa5db62fd04 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -72,6 +72,9 @@ typedef struct {
 #define	RAND_MAX	0x7fffffff
 
 __BEGIN_DECLS
+#ifdef _XLOCALE_H_
+#include <xlocale/_stdlib.h>
+#endif
 extern int __mb_cur_max;
 extern int ___mb_cur_max(void);
 #define	MB_CUR_MAX	(___mb_cur_max())
diff --git a/include/string.h b/include/string.h
index 074c20471910..e6a910b96fd3 100644
--- a/include/string.h
+++ b/include/string.h
@@ -133,7 +133,7 @@ void	 swab(const void * __restrict, void * __restrict, ssize_t);
 
 #endif /* __BSD_VISIBLE */
 
-#if __POSIX_VISIBLE >= 200809
+#if __POSIX_VISIBLE >= 200809 || defined(_XLOCALE_H_)
 #include <xlocale/_string.h>
 #endif
 __END_DECLS
diff --git a/include/time.h b/include/time.h
index 812575a86e71..19c948d646a7 100644
--- a/include/time.h
+++ b/include/time.h
@@ -184,7 +184,7 @@ time_t timelocal(struct tm * const);
 time_t timegm(struct tm * const);
 #endif /* __BSD_VISIBLE */
 
-#if __POSIX_VISIBLE >= 200809
+#if __POSIX_VISIBLE >= 200809 || defined(_XLOCALE_H_)
 #include <xlocale/_time.h>
 #endif
 __END_DECLS
diff --git a/include/wchar.h b/include/wchar.h
index 4e44b53633a1..1ebb72f58223 100644
--- a/include/wchar.h
+++ b/include/wchar.h
@@ -225,7 +225,7 @@ size_t	wcslcat(wchar_t *, const wchar_t *, size_t);
 size_t	wcslcpy(wchar_t *, const wchar_t *, size_t);
 #endif
 
-#if __POSIX_VISIBLE >= 200809
+#if __POSIX_VISIBLE >= 200809 || defined(_XLOCALE_H_)
 #include <xlocale/_wchar.h>
 #endif
 __END_DECLS