diff --git a/include/stdckdint.h b/include/stdckdint.h
--- a/include/stdckdint.h
+++ b/include/stdckdint.h
@@ -9,7 +9,7 @@
 
 #include <sys/cdefs.h>
 
-#if __BSD_VISIBLE || __ISO_C_VISIBLE >= 2023
+#if __ISO_C_VISIBLE >= 2023
 
 #if __GNUC_PREREQ__(5, 1) || __has_builtin(__builtin_add_overflow)
 #define ckd_add(result, a, b)						\
diff --git a/include/string.h b/include/string.h
--- a/include/string.h
+++ b/include/string.h
@@ -71,7 +71,7 @@
 void	*(mempcpy)(void * __restrict, const void * __restrict, size_t);
 #endif
 void	*(memset)(void *, int, size_t);
-#if __BSD_VISIBLE || __ISO_C_VISIBLE >= 2023
+#if __ISO_C_VISIBLE >= 2023
 void	*memset_explicit(void *, int, size_t);
 #endif
 #if __POSIX_VISIBLE >= 200809
diff --git a/include/strings.h b/include/strings.h
--- a/include/strings.h
+++ b/include/strings.h
@@ -42,7 +42,7 @@
 #endif
 
 __BEGIN_DECLS
-#if __BSD_VISIBLE || __POSIX_VISIBLE <= 200112
+#if __BSD_VISIBLE || (__POSIX_VISIBLE && __POSIX_VISIBLE <= 200112)
 int	 bcmp(const void *, const void *, size_t) __pure;	/* LEGACY */
 void	 (bcopy)(const void *, void *, size_t);			/* LEGACY */
 void	 (bzero)(void *, size_t);				/* LEGACY */
@@ -60,7 +60,7 @@
 int	 flsl(long) __pure2;
 int	 flsll(long long) __pure2;
 #endif
-#if __BSD_VISIBLE || __POSIX_VISIBLE <= 200112
+#if __BSD_VISIBLE || (__POSIX_VISIBLE && __POSIX_VISIBLE <= 200112)
 char	*index(const char *, int) __pure;			/* LEGACY */
 char	*rindex(const char *, int) __pure;			/* LEGACY */
 #endif
diff --git a/lib/msun/src/math.h b/lib/msun/src/math.h
--- a/lib/msun/src/math.h
+++ b/lib/msun/src/math.h
@@ -123,7 +123,7 @@
 /*
  * XOPEN/SVID
  */
-#if __BSD_VISIBLE || __XSI_VISIBLE
+#if __XSI_VISIBLE
 #define	M_E		2.7182818284590452354	/* e */
 #define	M_LOG2E		1.4426950408889634074	/* log 2e */
 #define	M_LOG10E	0.43429448190325182765	/* log 10e */
@@ -138,7 +138,7 @@
 #define	M_SQRT2		1.41421356237309504880	/* sqrt(2) */
 #define	M_SQRT1_2	0.70710678118654752440	/* 1/sqrt(2) */
 
-#if __BSD_VISIBLE || __XSI_VISIBLE >= 800
+#if __XSI_VISIBLE >= 800
 #define	M_El		2.718281828459045235360287471352662498L	/* e */
 #define	M_LOG2El	1.442695040888963407359924681001892137L	/* log_2 e */
 #define	M_LOG10El	0.434294481903251827651128918916605082L	/* log_10 e */
@@ -152,11 +152,11 @@
 #define	M_2_SQRTPIl	1.128379167095512573896158903121545172L	/* 2/sqrt(pi) */
 #define	M_SQRT2l	1.414213562373095048801688724209698079L	/* sqrt(2) */
 #define	M_SQRT1_2l	0.707106781186547524400844362104849039L	/* 1/sqrt(2) */
-#endif /* __BSD_VISIBLE || __XSI_VISIBLE >= 800 */
+#endif /* __XSI_VISIBLE >= 800 */
 
 #define	MAXFLOAT	((float)3.40282346638528860e+38)
 extern int signgam;
-#endif /* __BSD_VISIBLE || __XSI_VISIBLE */
+#endif /* __XSI_VISIBLE */
 
 #if __BSD_VISIBLE
 #if 0
@@ -264,7 +264,7 @@
 /*
  * These functions are not in C90.
  */
-#if __BSD_VISIBLE || __ISO_C_VISIBLE >= 1999 || __XSI_VISIBLE
+#if __ISO_C_VISIBLE >= 1999 || __XSI_VISIBLE
 double	acosh(double);
 double	asinh(double);
 double	atanh(double);
@@ -289,9 +289,9 @@
 double	remainder(double, double);
 double	remquo(double, double, int *);
 double	rint(double);
-#endif /* __BSD_VISIBLE || __ISO_C_VISIBLE >= 1999 || __XSI_VISIBLE */
+#endif /* __ISO_C_VISIBLE >= 1999 || __XSI_VISIBLE */
 
-#if __BSD_VISIBLE || __XSI_VISIBLE
+#if __XSI_VISIBLE
 double	j0(double);
 double	j1(double);
 double	jn(int, double);
@@ -308,7 +308,7 @@
 #endif
 #endif /* __BSD_VISIBLE || __XSI_VISIBLE */
 
-#if __BSD_VISIBLE || __ISO_C_VISIBLE >= 1999
+#if __ISO_C_VISIBLE >= 1999
 double	copysign(double, double) __pure2;
 double	fdim(double, double);
 double	fmax(double, double) __pure2;
diff --git a/sys/arm/include/setjmp.h b/sys/arm/include/setjmp.h
--- a/sys/arm/include/setjmp.h
+++ b/sys/arm/include/setjmp.h
@@ -96,7 +96,7 @@
 #define	_JB_REG_D15		46
 
 #ifndef __ASSEMBLER__
-#if __BSD_VISIBLE || __POSIX_VISIBLE || __XSI_VISIBLE
+#if __POSIX_VISIBLE || __XSI_VISIBLE
 typedef struct _sigjmp_buf { int _sjb[_JBLEN + 1]; } sigjmp_buf[1];
 #endif
 
diff --git a/sys/arm64/include/setjmp.h b/sys/arm64/include/setjmp.h
--- a/sys/arm64/include/setjmp.h
+++ b/sys/arm64/include/setjmp.h
@@ -65,7 +65,7 @@
  * compile-time diagnostics for mismatches.  The structs are the same
  * internally to avoid some run-time errors for mismatches.
  */
-#if __BSD_VISIBLE || __POSIX_VISIBLE || __XSI_VISIBLE
+#if __POSIX_VISIBLE || __XSI_VISIBLE
 typedef struct _sigjmp_buf { __int128_t _sjb[_JBLEN + 1]; } sigjmp_buf[1];
 #endif
 
diff --git a/sys/powerpc/include/setjmp.h b/sys/powerpc/include/setjmp.h
--- a/sys/powerpc/include/setjmp.h
+++ b/sys/powerpc/include/setjmp.h
@@ -18,7 +18,7 @@
  * compile-time diagnostics for mismatches.  The structs are the same
  * internally to avoid some run-time errors for mismatches.
  */
-#if __BSD_VISIBLE || __POSIX_VISIBLE || __XSI_VISIBLE
+#if __POSIX_VISIBLE || __XSI_VISIBLE
 typedef	struct _sigjmp_buf { long _sjb[_JBLEN + 1]; } sigjmp_buf[1];
 #endif
 
diff --git a/sys/riscv/include/setjmp.h b/sys/riscv/include/setjmp.h
--- a/sys/riscv/include/setjmp.h
+++ b/sys/riscv/include/setjmp.h
@@ -51,7 +51,7 @@
  * compile-time diagnostics for mismatches.  The structs are the same
  * internally to avoid some run-time errors for mismatches.
  */
-#if __BSD_VISIBLE || __POSIX_VISIBLE || __XSI_VISIBLE
+#if __POSIX_VISIBLE || __XSI_VISIBLE
 typedef	struct _sigjmp_buf { long _sjb[_JBLEN + 1] __aligned(16); } sigjmp_buf[1];
 #endif
 
diff --git a/sys/sys/_endian.h b/sys/sys/_endian.h
--- a/sys/sys/_endian.h
+++ b/sys/sys/_endian.h
@@ -67,14 +67,7 @@
 #error "Unsupported endian"
 #endif
 
-/*
- * POSIX Issue 8 will require these for endian.h. Define them there and in the
- * traditional BSD compilation environment. PDP_ENDIAN isn't strictly in Issue
- * 8, but is allowed as implementations can define any *_ENDIAN symbol. Since
- * issue 8 doesn't yet have an assigned date, use strictly greater than issue
- * 7's date.
- */
-#if __BSD_VISIBLE || _POSIX_C_SOURCE > 200809
+#if __POSIX_VISIBLE >= 202405
 #define	LITTLE_ENDIAN   _LITTLE_ENDIAN
 #define	BIG_ENDIAN      _BIG_ENDIAN
 #define	PDP_ENDIAN      _PDP_ENDIAN
diff --git a/sys/sys/signal.h b/sys/sys/signal.h
--- a/sys/sys/signal.h
+++ b/sys/sys/signal.h
@@ -445,7 +445,7 @@
 };
 #endif
 
-#if __BSD_VISIBLE || __POSIX_VISIBLE > 0 && __POSIX_VISIBLE <= 200112
+#if __POSIX_VISIBLE > 0 && __POSIX_VISIBLE <= 200112
 /*
  * Macro for converting signal number to a mask suitable for
  * sigblock().
diff --git a/sys/x86/include/setjmp.h b/sys/x86/include/setjmp.h
--- a/sys/x86/include/setjmp.h
+++ b/sys/x86/include/setjmp.h
@@ -41,7 +41,7 @@
  * compile-time diagnostics for mismatches.  The structs are the same
  * internally to avoid some run-time errors for mismatches.
  */
-#if __BSD_VISIBLE || __POSIX_VISIBLE || __XSI_VISIBLE
+#if __POSIX_VISIBLE || __XSI_VISIBLE
 typedef	struct _sigjmp_buf { long _sjb[_JBLEN]; } sigjmp_buf[1];
 #endif