diff --git a/libc/bionic/pthread_attr.cpp b/libc/bionic/pthread_attr.cpp
index 4b6a8f2..914dd36 100644
--- a/libc/bionic/pthread_attr.cpp
+++ b/libc/bionic/pthread_attr.cpp
@@ -164,7 +164,7 @@
   // Hunt for the region that contains that address.
   FILE* fp = fopen("/proc/self/maps", "re");
   if (fp == nullptr) {
-    async_safe_fatal("couldn't open /proc/self/maps");
+    async_safe_fatal("couldn't open /proc/self/maps: %s", strerror(errno));
   }
   char line[BUFSIZ];
   while (fgets(line, sizeof(line), fp) != NULL) {
diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index 9be86f1..5010a64 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -59,13 +59,13 @@
   size_t allocation_size = BIONIC_TLS_SIZE + 2 * PAGE_SIZE;
   void* allocation = mmap(nullptr, allocation_size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
   if (allocation == MAP_FAILED) {
-    async_safe_fatal("failed to allocate TLS");
+    async_safe_fatal("failed to allocate TLS: %s", strerror(errno));
   }
   prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, allocation, allocation_size, "bionic TLS guard page");
 
   thread->bionic_tls = reinterpret_cast<bionic_tls*>(static_cast<char*>(allocation) + PAGE_SIZE);
   if (mprotect(thread->bionic_tls, BIONIC_TLS_SIZE, PROT_READ | PROT_WRITE) != 0) {
-    async_safe_fatal("failed to mprotect TLS");
+    async_safe_fatal("failed to mprotect TLS: %s", strerror(errno));
   }
   prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, thread->bionic_tls, BIONIC_TLS_SIZE, "bionic TLS");
 }
diff --git a/libc/upstream-openbsd/android/include/arc4random.h b/libc/upstream-openbsd/android/include/arc4random.h
index d006045..4c4be0e 100644
--- a/libc/upstream-openbsd/android/include/arc4random.h
+++ b/libc/upstream-openbsd/android/include/arc4random.h
@@ -45,10 +45,8 @@
 #define _ARC4_ATFORK(f) pthread_atfork(NULL, NULL, (f))
 #endif
 
-static inline void
-_getentropy_fail(void)
-{
-	async_safe_fatal("getentropy failed");
+static inline void _getentropy_fail(void) {
+    async_safe_fatal("getentropy failed: %s", strerror(errno));
 }
 
 volatile sig_atomic_t _rs_forked;