diff --git a/libc/dns/freeaddrinfo.c b/libc/dns/freeaddrinfo.c
index 782b20afe..147323056 100644
--- a/libc/dns/freeaddrinfo.c
+++ b/libc/dns/freeaddrinfo.c
@@ -21,6 +21,7 @@
 
 /**
  * Frees addresses returned by getaddrinfo().
+ * @threadsafe
  */
 int freeaddrinfo(struct addrinfo *ai) {
   struct addrinfo *next;
diff --git a/libc/dns/getaddrinfo.c b/libc/dns/getaddrinfo.c
index b30ce2e32..f07b10bc6 100644
--- a/libc/dns/getaddrinfo.c
+++ b/libc/dns/getaddrinfo.c
@@ -41,6 +41,7 @@
  * @param res receives a pointer that must be freed with freeaddrinfo(),
  *     and won't be modified if -1 is returned
  * @return 0 on success or EAI_xxx value
+ * @threadsafe
  */
 int getaddrinfo(const char *name, const char *service,
                 const struct addrinfo *hints, struct addrinfo **res) {
diff --git a/libc/dns/gethoststxt.c b/libc/dns/gethoststxt.c
index 16598bdde..95cd09bec 100644
--- a/libc/dns/gethoststxt.c
+++ b/libc/dns/gethoststxt.c
@@ -23,6 +23,7 @@
 #include "libc/dce.h"
 #include "libc/dns/hoststxt.h"
 #include "libc/fmt/fmt.h"
+#include "libc/intrin/pthread.h"
 #include "libc/macros.internal.h"
 #include "libc/nt/systeminfo.h"
 #include "libc/runtime/runtime.h"
@@ -32,6 +33,7 @@
 static struct HostsTxt *g_hoststxt;
 static struct HostsTxtInitialStaticMemory {
   struct HostsTxt ht;
+  pthread_mutex_t lock;
   struct HostsTxtEntry entries[8];
   char strings[64];
 } g_hoststxt_init;
@@ -53,6 +55,7 @@ static textwindows dontinline char *GetNtHostsTxtPath(char *pathbuf,
  * Returns hosts.txt map.
  *
  * @note yoinking realloc() ensures there's no size limits
+ * @threadsafe
  */
 const struct HostsTxt *GetHostsTxt(void) {
   FILE *f;
@@ -60,6 +63,7 @@ const struct HostsTxt *GetHostsTxt(void) {
   char pathbuf[PATH_MAX];
   struct HostsTxtInitialStaticMemory *init;
   init = &g_hoststxt_init;
+  pthread_mutex_lock(&init->lock);
   if (!g_hoststxt) {
     g_hoststxt = &init->ht;
     init->ht.entries.n = pushpop(ARRAYLEN(init->entries));
@@ -78,5 +82,6 @@ const struct HostsTxt *GetHostsTxt(void) {
       fclose(f);
     }
   }
+  pthread_mutex_unlock(&init->lock);
   return g_hoststxt;
 }
diff --git a/libc/dns/getresolvconf.c b/libc/dns/getresolvconf.c
index 3681d9d12..df1d00537 100644
--- a/libc/dns/getresolvconf.c
+++ b/libc/dns/getresolvconf.c
@@ -20,6 +20,7 @@
 #include "libc/dce.h"
 #include "libc/dns/resolvconf.h"
 #include "libc/fmt/fmt.h"
+#include "libc/intrin/pthread.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sock/sock.h"
@@ -28,17 +29,20 @@
 static struct ResolvConf *g_resolvconf;
 static struct ResolvConfInitialStaticMemory {
   struct ResolvConf rv;
+  pthread_mutex_t lock;
   struct sockaddr_in nameservers[3];
 } g_resolvconf_init;
 
 /**
  * Returns singleton with DNS server address.
+ * @threadsafe
  */
 const struct ResolvConf *GetResolvConf(void) {
   int rc;
   FILE *f;
   struct ResolvConfInitialStaticMemory *init;
   init = &g_resolvconf_init;
+  pthread_mutex_lock(&init->lock);
   if (!g_resolvconf) {
     g_resolvconf = &init->rv;
     pushmov(&init->rv.nameservers.n, ARRAYLEN(init->nameservers));
@@ -58,5 +62,6 @@ const struct ResolvConf *GetResolvConf(void) {
       /* TODO(jart): Elevate robustness. */
     }
   }
+  pthread_mutex_unlock(&init->lock);
   return g_resolvconf;
 }
diff --git a/libc/dns/lookupservicesbyname.c b/libc/dns/lookupservicesbyname.c
index 14458531e..d6046fabf 100644
--- a/libc/dns/lookupservicesbyname.c
+++ b/libc/dns/lookupservicesbyname.c
@@ -47,6 +47,7 @@
  * @return -1 on error, or positive port number
  * @note aliases are read from file for comparison, but not returned.
  * @see LookupServicesByPort
+ * @threadsafe
  */
 int LookupServicesByName(const char *servname, char *servproto,
                          size_t servprotolen, char *buf, size_t bufsize,
diff --git a/libc/log/cxaprintexits.c b/libc/log/cxaprintexits.c
index a02d77490..54bae4ee2 100644
--- a/libc/log/cxaprintexits.c
+++ b/libc/log/cxaprintexits.c
@@ -37,6 +37,7 @@ void __cxa_printexits(FILE *f, void *pred) {
   fprintf(f, "                       GLOBAL DESTRUCTORS                   \n");
   fprintf(f, "      callback                arg                pred       \n");
   fprintf(f, "---------------------- ------------------ ------------------\n");
+  __cxa_lock();
   if ((b = __cxa_blocks.p)) {
     do {
       mask = b->mask;
@@ -56,5 +57,6 @@ void __cxa_printexits(FILE *f, void *pred) {
       }
     } while ((b = b->next));
   }
+  __cxa_unlock();
   fprintf(f, "\n");
 }
diff --git a/libc/macros.internal.inc b/libc/macros.internal.inc
index 15772f719..29cf280fd 100644
--- a/libc/macros.internal.inc
+++ b/libc/macros.internal.inc
@@ -127,10 +127,6 @@
 //	Loads address of errno into %rcx
 .macro	.errno
 	call	__errno_location
-//	cs
-//	cs
-//	cs
-//	mov	$__errno,%eax
 .endm
 
 //	Post-Initialization Read-Only (PIRO) BSS section.
diff --git a/libc/runtime/cosmo.S b/libc/runtime/cosmo.S
index 97f228013..adc19feaa 100644
--- a/libc/runtime/cosmo.S
+++ b/libc/runtime/cosmo.S
@@ -124,6 +124,16 @@ cosmo:	push	%rbp
 	.weak	ape_stack_align
 #endif
 
+#if IsAsan()
+	.init.start 305,_init_symbols
+	push	%rdi
+	push	%rsi
+	call	__init_symbols
+	pop	%rsi
+	pop	%rdi
+	.init.end 305,_init_symbols
+#endif
+
 #ifdef __PG__
 	.init.start 306,_init_ftrace
 	push	%rdi
@@ -135,16 +145,6 @@ cosmo:	push	%rbp
 	.init.end 306,_init_ftrace
 #endif
 
-#if IsAsan()
-	.init.start 306,_init_symbols
-	push	%rdi
-	push	%rsi
-	call	__init_symbols
-	pop	%rsi
-	pop	%rdi
-	.init.end 306,_init_symbols
-#endif
-
 #if IsModeDbg()
 #ifdef SYSDEBUG
 	.init.start 307,_init_printargs
diff --git a/libc/sock/firewall.c b/libc/sock/firewall.c
index 10bdfb4b7..890c75454 100644
--- a/libc/sock/firewall.c
+++ b/libc/sock/firewall.c
@@ -20,6 +20,8 @@
 #include "libc/calls/calls.h"
 #include "libc/dce.h"
 #include "libc/log/log.h"
+#include "libc/runtime/internal.h"
+#include "libc/runtime/runtime.h"
 #include "libc/sock/internal.h"
 #include "libc/sock/sock.h"
 #include "libc/sysv/consts/af.h"
@@ -42,6 +44,7 @@ void _firewall(const void *addr, uint32_t addrsize) {
     *p++ = '\n';
     write(2, b, p - b);
     if (weaken(__die)) weaken(__die)();
-    abort();
+    __restorewintty();
+    _Exit(66);
   }
 }