diff --git a/libc/calls/getauxval.c b/libc/calls/getauxval.c
index 435eb7952..4b4ab9d5e 100644
--- a/libc/calls/getauxval.c
+++ b/libc/calls/getauxval.c
@@ -36,26 +36,10 @@ unsigned long getauxval(unsigned long at) {
   if (at != -1) {
     if (!IsWindows()) {
       if (!g_auxv) return 0;
-      if (IsXnu()) {
-        if (at) {
-          const char *name =
-              at == AT_EXECFN ? "executable_path" : (const char *)at;
-          const char **auxv = (const char **)g_auxv;
-          unsigned namelen = strlen(name);
-          for (int i = 0; auxv[i]; ++i) {
-            if (strncmp(auxv[i], name, namelen) == 0 &&
-                auxv[i][namelen] == '=') {
-              res = (intptr_t)&auxv[i][namelen + 1];
-              break;
-            }
-          }
-        }
-      } else {
-        for (const unsigned long *ap = g_auxv; *ap; ap += 2) {
-          if (ap[0] == at) {
-            res = ap[1];
-            break;
-          }
+      for (const unsigned long *ap = g_auxv; *ap; ap += 2) {
+        if (ap[0] == at) {
+          res = ap[1];
+          break;
         }
       }
     } else {
diff --git a/libc/crt/crt.S b/libc/crt/crt.S
index 519b11de7..f65ac82db 100644
--- a/libc/crt/crt.S
+++ b/libc/crt/crt.S
@@ -52,11 +52,23 @@ _start:	test	%rdi,%rdi
 	mov	%rdx,%rdi
 	repnz scasq
 	mov	%rdi,%rcx			# auxv
-	mov	%ebx,%edi
+#if SupportsXnu()
+	testb	IsXnu()
+	jz	1f				# polyfill xnu auxv
+	push	$0				# auxv[1][1]=0
+	push	$0				# auxv[1][0]=0
+	mov	(%rcx),%rax			# executable_path=BIN
+	lea	16(%rax),%rax			# BIN
+	push	%rax				# auxv[0][0]=BIN
+	push	$31				# auxv[0][0]=AT_EXECFN
+	mov	%rsp,%rcx			# auxv
+#endif
+1:	mov	%ebx,%edi
 	call	cosmo
 9:	ud2
 	.endfn	_start,weak,hidden
 
+#if SupportsXnu()
 /	Macintosh userspace program entrypoint.
 /
 /	@param	rsp is [n,argv₀..argvₙ₋₁,0,envp₀..,0,auxv₀..,0,..]
@@ -65,3 +77,4 @@ _start:	test	%rdi,%rdi
 _xnu:	movb	$XNU,__hostos(%rip)
 	jmp	0b
 	.endfn	_xnu,weak,hidden
+#endif
diff --git a/libc/intrin/asan.c b/libc/intrin/asan.c
index f2a61c503..70dbdd877 100644
--- a/libc/intrin/asan.c
+++ b/libc/intrin/asan.c
@@ -77,12 +77,11 @@ STATIC_YOINK("_init_asan");
     }                       \
   } while (0)
 
-#define REQUIRE(FUNC)                                \
-  do {                                               \
-    if (!weaken(FUNC)) {                             \
-      __asan_write_string("asan needs " #FUNC "\n"); \
-      __asan_exit(100);                              \
-    }                                                \
+#define REQUIRE(FUNC)                              \
+  do {                                             \
+    if (!weaken(FUNC)) {                           \
+      __asan_die("error: asan needs " #FUNC "\n"); \
+    }                                              \
   } while (0)
 
 struct AsanSourceLocation {
@@ -448,7 +447,6 @@ static ssize_t __asan_write_string(const char *s) {
 
 static wontreturn void __asan_abort(void) {
   if (weaken(__die)) weaken(__die)();
-  if (weaken(abort)) weaken(abort)();
   __asan_exit(134);
 }
 
@@ -753,7 +751,7 @@ void __asan_map_shadow(uintptr_t p, size_t n) {
           weaken(TrackMemoryInterval)(
               m, a, a, sm.maphandle, PROT_READ | PROT_WRITE,
               MAP_PRIVATE | *weaken(MAP_ANONYMOUS) | MAP_FIXED) == -1) {
-        __asan_abort();
+        __asan_die("error: could not map asan shadow memory\n");
       }
       __asan_repstosb((void *)((uintptr_t)a << 16), kAsanUnmapped, 1 << 16);
     }
diff --git a/libc/runtime/winmain.greg.c b/libc/runtime/winmain.greg.c
index b425cfb16..00f8010a2 100644
--- a/libc/runtime/winmain.greg.c
+++ b/libc/runtime/winmain.greg.c
@@ -67,7 +67,7 @@ static noasan textwindows void MakeLongDoubleLongAgain(void) {
 static noasan textwindows void NormalizeCmdExe(void) {
   uint32_t mode;
   int64_t handle, hstdin, hstdout, hstderr;
-  if ((int)weakaddr("sys_v_ntsubsystem") == kNtImageSubsystemWindowsCui &&
+  if ((int)weakaddr("v_ntsubsystem") == kNtImageSubsystemWindowsCui &&
       NtGetVersion() >= kNtVersionWindows10) {
     hstdin = GetStdHandle(pushpop(kNtStdInputHandle));
     hstdout = GetStdHandle(pushpop(kNtStdOutputHandle));
diff --git a/libc/sysv/consts.sh b/libc/sysv/consts.sh
index 451a081b5..a8d798b50 100755
--- a/libc/sysv/consts.sh
+++ b/libc/sysv/consts.sh
@@ -461,7 +461,7 @@ syscon	auxv	AT_UCACHEBSIZE				21			0			0			0			0
 syscon	auxv	AT_SECURE				23			0			0			0			0
 syscon	auxv	AT_BASE_PLATFORM			24			0			0			0			0
 syscon	auxv	AT_RANDOM				25			0			0			0			0			# address of sixteen bytes of random data
-syscon	auxv	AT_EXECFN				31			999			999			999			999			# address of string containing first argument passed to execve() used when running program [faked on non-linux]
+syscon	auxv	AT_EXECFN				31			31			999			999			999			# address of string containing first argument passed to execve() used when running program [faked on non-linux]
 syscon	auxv	AT_SYSINFO_EHDR				33			0			0			0			0
 syscon	auxv	AT_NO_AUTOMOUNT				0x0800			0			0			0			0
 
diff --git a/libc/sysv/consts/AT_EXECFN.s b/libc/sysv/consts/AT_EXECFN.s
index 621655d9f..97900473b 100644
--- a/libc/sysv/consts/AT_EXECFN.s
+++ b/libc/sysv/consts/AT_EXECFN.s
@@ -1,2 +1,2 @@
 .include "libc/sysv/consts/syscon.inc"
-.syscon auxv AT_EXECFN 31 999 999 999 999
+.syscon auxv AT_EXECFN 31 31 999 999 999