diff --git a/include/assert.h b/include/assert.h
index afbf2c1092e0..d474169719c6 100644
--- a/include/assert.h
+++ b/include/assert.h
@@ -68,8 +68,10 @@
 #endif /* __BSD_VISIBLE */
 #endif /* NDEBUG */
 
-#ifndef __STDC_VERSION_ASSERT_H__
-#define __STDC_VERSION_ASSERT_H__ 202311L
+#ifndef _ASSERT_H_
+#define _ASSERT_H_
+
+#define __STDC_VERSION_ASSERT_H__	202311L
 
 /*
  * Static assertions.  In principle we could define static_assert for
@@ -92,4 +94,4 @@ __BEGIN_DECLS
 void __assert(const char *, const char *, int, const char *) __dead2;
 __END_DECLS
 
-#endif /* !__STDC_VERSION_ASSERT_H__ */
+#endif /* !_ASSERT_H_ */
diff --git a/include/limits.h b/include/limits.h
index 7b316e6e905d..5e7e0317d42e 100644
--- a/include/limits.h
+++ b/include/limits.h
@@ -29,7 +29,9 @@
  * SUCH DAMAGE.
  */
 
-#ifndef __STDC_VERSION_LIMITS_H__
+#ifndef _LIMITS_H_
+#define _LIMITS_H_
+
 #define __STDC_VERSION_LIMITS_H__	202311L
 
 #include <sys/cdefs.h>
@@ -148,4 +150,4 @@
 #include <sys/syslimits.h>
 #endif
 
-#endif /* !__STDC_VERSION_LIMITS_H__ */
+#endif /* !_LIMITS_H_ */
diff --git a/include/rpc/xdr.h b/include/rpc/xdr.h
index 1b480ca0dd34..4c75bcc5bbf7 100644
--- a/include/rpc/xdr.h
+++ b/include/rpc/xdr.h
@@ -332,7 +332,7 @@ __BEGIN_DECLS
 extern void   xdrmem_create(XDR *, char *, u_int, enum xdr_op);
 
 /* XDR using stdio library */
-#ifdef __STDC_VERSION_STDIO_H__
+#ifdef _STDIO_H_
 extern void   xdrstdio_create(XDR *, FILE *, enum xdr_op);
 #endif
 
diff --git a/include/stdio.h b/include/stdio.h
index 50e3ff2d1c34..566dddb76925 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -32,7 +32,9 @@
  * SUCH DAMAGE.
  */
 
-#ifndef __STDC_VERSION_STDIO_H__
+#ifndef	_STDIO_H_
+#define	_STDIO_H_
+
 #define __STDC_VERSION_STDIO_H__	202311L
 
 #include <sys/cdefs.h>
@@ -540,4 +542,4 @@ extern int __isthreaded;
 __END_DECLS
 __NULLABILITY_PRAGMA_POP
 
-#endif /* !__STDC_VERSION_STDIO_H__ */
+#endif /* !_STDIO_H_ */
diff --git a/include/xlocale.h b/include/xlocale.h
index b1c83592a619..cc2fc0839593 100644
--- a/include/xlocale.h
+++ b/include/xlocale.h
@@ -68,7 +68,7 @@ __BEGIN_DECLS
 #include <xlocale/_ctype.h>
 #endif
 
-#ifdef __STDC_VERSION_STDIO_H__
+#ifdef _STDIO_H_
 #include <xlocale/_stdio.h>
 #endif
 
diff --git a/lib/libc/xdr/xdr.3 b/lib/libc/xdr/xdr.3
index 5d81a867ad66..65adb050fa44 100644
--- a/lib/libc/xdr/xdr.3
+++ b/lib/libc/xdr/xdr.3
@@ -572,7 +572,7 @@ This routine returns the amount of memory required to encode
 using filter
 .Fa func .
 .Pp
-.It Li "#ifdef __STDC_VERSION_STDIO_H__"
+.It Li "#ifdef _STDIO_H_"
 .It Li "/* XDR using stdio library */"
 .It Xo
 .Ft void
diff --git a/lib/libgeom/libgeom.h b/lib/libgeom/libgeom.h
index 713c49f0380c..2116645bd496 100644
--- a/lib/libgeom/libgeom.h
+++ b/lib/libgeom/libgeom.h
@@ -143,7 +143,7 @@ void geom_deletetree(struct gmesh *);
 
 struct gctl_req;
 
-#ifdef __STDC_VERSION_STDIO_H__		/* limit #include pollution */
+#ifdef _STDIO_H_			/* limit #include pollution */
 void gctl_dump(struct gctl_req *, FILE *);
 #endif
 void gctl_free(struct gctl_req *);
diff --git a/lib/libutil/libutil.h b/lib/libutil/libutil.h
index 679a213e64bf..17e4f1fba247 100644
--- a/lib/libutil/libutil.h
+++ b/lib/libutil/libutil.h
@@ -151,7 +151,7 @@ int	uu_lock_txfr(const char *_ttyname, pid_t _pid);
  * Conditionally prototype the following functions if the include
  * files upon which they depend have been included.
  */
-#ifdef __STDC_VERSION_STDIO_H__
+#ifdef _STDIO_H_
 char	*fparseln(FILE *_fp, size_t *_len, size_t *_lineno,
 	    const char _delim[3], int _flags);
 #endif
diff --git a/stand/libsa/geli/geliboot_internal.h b/stand/libsa/geli/geliboot_internal.h
index 6b7b5742408e..50157f24c7f5 100644
--- a/stand/libsa/geli/geliboot_internal.h
+++ b/stand/libsa/geli/geliboot_internal.h
@@ -28,15 +28,9 @@
 #ifndef _GELIBOOT_INTERNAL_H_
 #define _GELIBOOT_INTERNAL_H_
 
-/*
- * XXX:
- * The following deliberate defines are to keep g_eli.h from including
- * unnecessary headers.  It would be preferable to conditionally include
- * them in a _STANDALONE branch there instead.
- */
 #define _STRING_H_
 #define _STRINGS_H_
-#define __STDC_VERSION_STDIO_H__	202311L
+#define _STDIO_H_
 
 #include <sys/endian.h>
 #include <sys/queue.h>
diff --git a/sys/sys/stdatomic.h b/sys/sys/stdatomic.h
index 24be02e247a3..cc1e31f658a4 100644
--- a/sys/sys/stdatomic.h
+++ b/sys/sys/stdatomic.h
@@ -27,7 +27,9 @@
  * SUCH DAMAGE.
  */
 
-#ifndef __STDC_VERSION_STDATOMIC_H__
+#ifndef _STDATOMIC_H_
+#define _STDATOMIC_H_
+
 #define __STDC_VERSION_STDATOMIC_H__	202311L
 
 #include <sys/cdefs.h>
@@ -438,4 +440,4 @@ atomic_flag_clear(volatile atomic_flag *__object)
 #undef __bool_locally_defined
 #endif
 
-#endif /* !__STDC_VERSION_STDATOMIC_H__ */
+#endif /* !_STDATOMIC_H_ */
diff --git a/sys/sys/syslimits.h b/sys/sys/syslimits.h
index eb1520d98c89..84a39d36fda2 100644
--- a/sys/sys/syslimits.h
+++ b/sys/sys/syslimits.h
@@ -33,7 +33,7 @@
 #define _SYS_SYSLIMITS_H_
 
 #if !defined(_STANDALONE) && !defined(_KERNEL) && \
-    !defined(__STDC_VERSION_LIMITS_H__) && !defined(_SYS_PARAM_H_)
+    !defined(_LIMITS_H_) && !defined(_SYS_PARAM_H_)
 #warning "No user-serviceable parts inside."
 #endif