diff --git a/include/compat/bionic_host_libc_runtime.h b/include/compat/bionic_host_libc_runtime.h
index be55994..0a363ff 100644
--- a/include/compat/bionic_host_libc_runtime.h
+++ b/include/compat/bionic_host_libc_runtime.h
@@ -11,6 +11,14 @@
 
 namespace mocktail::compat {
 
+// glibc's atoi is (int)strtol(), exactly like Bionic's, so the host symbol is
+// used as-is there. Other libcs (musl) differ on overflow and need the shim.
+#ifdef __GLIBC__
+inline constexpr bool kHostAtoiMatchesBionic = true;
+#else
+inline constexpr bool kHostAtoiMatchesBionic = false;
+#endif
+
 // Android uses size_t fields here; glibc uses int and musl has no equivalent.
 // An all-zero fallback means unknown, not zero usage.
 struct BionicMallinfoSnapshot {
diff --git a/src/compat/bionic_host_libc_runtime.cc b/src/compat/bionic_host_libc_runtime.cc
index d1d6cd6..396b6ba 100644
--- a/src/compat/bionic_host_libc_runtime.cc
+++ b/src/compat/bionic_host_libc_runtime.cc
@@ -150,6 +150,15 @@ Result ParseInHostCLocale(Parser parser) noexcept {
   return result;
 }
 
+// Highest errno in Bionic's message table (EHWPOISON). Numbers 41 and 58 are
+// unassigned in the generic Linux errno list, so Bionic has no text for them.
+constexpr int kBionicMaxErrno = 133;
+
+constexpr bool HasBionicErrnoMessage(int error_number) noexcept {
+  return error_number >= 0 && error_number <= kBionicMaxErrno &&
+         error_number != 41 && error_number != 58;
+}
+
 template <typename Result>
 const char* HostStrErrorResult(Result result, char* buffer) noexcept {
   if constexpr (std::is_integral_v<Result>) {
@@ -318,18 +327,19 @@ int BionicStrError(int error_number, char* buffer,
     return -1;
   }
 
+  // Bionic's table ends at EHWPOISON. Unknown numbers get the same text on
+  // every host instead of whatever the host libc prints (musl has no
+  // "Unknown error N" form).
   std::array<char, 256> host_buffer{};
-  auto host_result =
-      ::strerror_r(error_number, host_buffer.data(), host_buffer.size());
-  const char* message = HostStrErrorResult(host_result, host_buffer.data());
+  const char* message = nullptr;
+  if (HasBionicErrnoMessage(error_number)) {
+    auto host_result =
+        ::strerror_r(error_number, host_buffer.data(), host_buffer.size());
+    message = HostStrErrorResult(host_result, host_buffer.data());
+  }
 
-  std::array<char, 256> unknown_buffer{};
-  const char* unknown_message = HostStrErrorResult(
-      ::strerror_r(-1, unknown_buffer.data(), unknown_buffer.size()),
-      unknown_buffer.data());
-  if (message == nullptr ||
-      (error_number != 0 && unknown_message != nullptr &&
-       std::strcmp(message, unknown_message) == 0)) {
+  std::array<char, 64> unknown_buffer{};
+  if (message == nullptr) {
     std::snprintf(unknown_buffer.data(), unknown_buffer.size(),
                   "Unknown error %d", error_number);
     message = unknown_buffer.data();
diff --git a/src/linker/linker.cc b/src/linker/linker.cc
index e8461cb..1ae1d22 100644
--- a/src/linker/linker.cc
+++ b/src/linker/linker.cc
@@ -134,7 +134,8 @@ bool IsBionicLibcOnlySymbol(std::string_view symbol) {
   }
   return symbol == "__cmsg_nxthdr" || symbol == "__cxa_thread_atexit_impl" ||
          symbol == "__readlink_chk" || symbol == "__register_atfork" ||
-         symbol == "arc4random_buf" || symbol == "atoi" || symbol == "geteuid" ||
+         symbol == "arc4random_buf" || symbol == "geteuid" ||
+         (!mocktail::compat::kHostAtoiMatchesBionic && symbol == "atoi") ||
          symbol == "getuid" || symbol == "lseek64" ||
          symbol == "mallinfo" || symbol == "pread64" || symbol == "pwrite64" ||
          symbol == "sigaction" || symbol == "strerror_r" ||
@@ -384,8 +385,10 @@ void RegisterBionicHostLibcRuntimeForLibc() {
   RegisterSyntheticSymbol("libc.so", "arc4random_buf",
                           reinterpret_cast<void*>(
                               mocktail_bionic_arc4random_buf));
-  RegisterSyntheticSymbol("libc.so", "atoi",
-                          reinterpret_cast<void*>(mocktail_bionic_atoi));
+  if (!mocktail::compat::kHostAtoiMatchesBionic) {
+    RegisterSyntheticSymbol("libc.so", "atoi",
+                            reinterpret_cast<void*>(mocktail_bionic_atoi));
+  }
   RegisterSyntheticSymbol("libc.so", "mallinfo",
                           reinterpret_cast<void*>(mocktail_bionic_mallinfo));
   RegisterSyntheticSymbol("libc.so", "sysinfo",
diff --git a/tests/bionic_host_libc_runtime_test.cc b/tests/bionic_host_libc_runtime_test.cc
index 2809cb0..4f889c9 100644
--- a/tests/bionic_host_libc_runtime_test.cc
+++ b/tests/bionic_host_libc_runtime_test.cc
@@ -234,7 +234,7 @@ TEST(BionicHostLibcRuntimeTest, UsesBionicPosixStrErrorContract) {
   EXPECT_STREQ(buffer.data(), std::strerror(0));
   EXPECT_EQ(errno, EDOM);
 
-  for (const int error_number : {-1, 4567, INT_MIN, INT_MAX}) {
+  for (const int error_number : {-1, 41, 58, 134, 4567, INT_MIN, INT_MAX}) {
     errno = EDOM;
     ASSERT_EQ(mocktail_bionic_strerror_r(error_number, buffer.data(),
                                        buffer.size()), 0);
diff --git a/tests/linker_registry_test.cc b/tests/linker_registry_test.cc
index 75816bd..a627369 100644
--- a/tests/linker_registry_test.cc
+++ b/tests/linker_registry_test.cc
@@ -130,8 +130,12 @@ TEST(LinkerRegistryTest, KeepsHostIndependentBionicAbiOwnedByLibc) {
             reinterpret_cast<void *>(mocktail___readlink_chk));
   EXPECT_EQ(symbols.at("arc4random_buf"),
             reinterpret_cast<void *>(mocktail_bionic_arc4random_buf));
-  EXPECT_EQ(symbols.at("atoi"),
-            reinterpret_cast<void *>(mocktail_bionic_atoi));
+  if (mocktail::compat::kHostAtoiMatchesBionic) {
+    EXPECT_EQ(symbols.count("atoi"), 0u);
+  } else {
+    EXPECT_EQ(symbols.at("atoi"),
+              reinterpret_cast<void *>(mocktail_bionic_atoi));
+  }
   EXPECT_EQ(symbols.at("mallinfo"),
             reinterpret_cast<void *>(mocktail_bionic_mallinfo));
   EXPECT_EQ(symbols.at("sysinfo"),