diff --git a/libc/crt/crt.S b/libc/crt/crt.S
index cc8ae2f35..3340181f3 100644
--- a/libc/crt/crt.S
+++ b/libc/crt/crt.S
@@ -127,7 +127,7 @@ _start:
 
 #if SupportsFreebsd()
 //	save first arg
-	mov	x3,x0
+	mov	x4,x0
 #endif
 
 //	save original stack pointer
diff --git a/libc/runtime/cosmo2.c b/libc/runtime/cosmo2.c
index 7326b22b6..c1f5b9b34 100644
--- a/libc/runtime/cosmo2.c
+++ b/libc/runtime/cosmo2.c
@@ -79,7 +79,7 @@ static const char *DecodeMagnum(const char *p, long *r) {
 }
 
 wontreturn textstartup void cosmo(long *sp, struct Syslib *m1, char *exename,
-                                  long *is_freebsd) {
+                                  int os, long *is_freebsd) {
 
   // get startup timestamp as early as possible
   // its used by --strace and also kprintf() %T
@@ -117,17 +117,27 @@ wontreturn textstartup void cosmo(long *sp, struct Syslib *m1, char *exename,
   __program_executable_name = exename;
   program_invocation_name = argv[0];
   __oldstack = (intptr_t)sp;
+  if (!(hostos = os)) {
+    if (SupportsFreebsd() && is_freebsd) {
+      hostos = _HOSTFREEBSD;
+    } else if (SupportsXnu() && m1) {
+      hostos = _HOSTXNU;
+    } else if (SupportsLinux()) {
+      hostos = _HOSTLINUX;
+    } else {
+      notpossible;
+    }
+  }
 
-  // detect apple m1 environment
   const char *magnums;
-  if (SupportsFreebsd() && is_freebsd) {
-    hostos = _HOSTFREEBSD;
+  if (IsFreebsd()) {
     magnums = syscon_freebsd;
-  } else if (SupportsXnu() && (__syslib = m1)) {
-    hostos = _HOSTXNU;
+  } else if (IsXnu()) {
+    if (!(__syslib = m1)) {
+      notpossible;
+    }
     magnums = syscon_xnu;
-  } else if (SupportsLinux()) {
-    hostos = _HOSTLINUX;
+  } else if (IsLinux()) {
     magnums = syscon_linux;
   } else {
     notpossible;
@@ -139,7 +149,7 @@ wontreturn textstartup void cosmo(long *sp, struct Syslib *m1, char *exename,
   }
 
   // check system call abi compatibility
-  if (SupportsXnu() && __syslib && __syslib->__version < SYSLIB_VERSION) {
+  if (IsXnu() && __syslib->__version < SYSLIB_VERSION) {
     sys_write(2, "need newer ape loader\n", 22);
     _Exit(127);
   }