diff --git a/core/libs/CMakeLists.txt b/core/libs/CMakeLists.txt
index 209da779b..686be48ce 100644
--- a/core/libs/CMakeLists.txt
+++ b/core/libs/CMakeLists.txt
@@ -104,6 +104,15 @@ endforeach()
 add_custom_target(libs DEPENDS ${PATCHED_OUTPUTS})
 
 if(BUILD_TESTING)
+    add_executable(guest_error_tests tests/GuestErrors.cpp)
+    target_include_directories(guest_error_tests PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+    target_link_libraries(guest_error_tests PRIVATE libc)
+    configure_windows_unwind(guest_error_tests)
+    add_test(NAME guest_errors COMMAND guest_error_tests)
+    if(WIN32)
+        set_tests_properties(guest_errors PROPERTIES ENVIRONMENT_MODIFICATION
+            "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
+    endif()
     add_executable(guest_resolver_tests tests/GuestResolver.cpp)
     target_include_directories(guest_resolver_tests PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
     target_link_libraries(guest_resolver_tests PRIVATE libScePosixForWebKit)
diff --git a/core/libs/prx/libc/CMakeLists.txt b/core/libs/prx/libc/CMakeLists.txt
index b3428c80d..574558de6 100644
--- a/core/libs/prx/libc/CMakeLists.txt
+++ b/core/libs/prx/libc/CMakeLists.txt
@@ -18,6 +18,7 @@ target_sources(libc PRIVATE
         ${CMAKE_CURRENT_SOURCE_DIR}/src/RuntimeSupport.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/LocaleSupport.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/Process.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/src/Errors.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/CxxAbiSupport.cpp
         ${CMAKE_CURRENT_SOURCE_DIR}/src/exception/Exports.cpp
 )
diff --git a/core/libs/prx/libc/src/Errors.cpp b/core/libs/prx/libc/src/Errors.cpp
new file mode 100644
index 000000000..963191cf6
--- /dev/null
+++ b/core/libs/prx/libc/src/Errors.cpp
@@ -0,0 +1,75 @@
+#include "prx/libc/include/general/VabiMacros.hpp"
+#include <cstdio>
+#include <cstring>
+
+extern "C" int* APS5_VABI __error_nid_postfix();
+
+namespace {
+// Guest FreeBSD errno numbering, not the host CRT's numbering.
+constexpr const char* messages[] = {
+    "No error", "Operation not permitted", "No such file or directory", "No such process",
+    "Interrupted system call", "Input/output error", "Device not configured", "Argument list too long",
+    "Exec format error", "Bad file descriptor", "No child processes", "Resource deadlock avoided",
+    "Cannot allocate memory", "Permission denied", "Bad address", "Block device required",
+    "Device busy", "File exists", "Cross-device link", "Operation not supported by device",
+    "Not a directory", "Is a directory", "Invalid argument", "Too many open files in system",
+    "Too many open files", "Inappropriate ioctl for device", "Text file busy", "File too large",
+    "No space left on device", "Illegal seek", "Read-only filesystem", "Too many links", "Broken pipe",
+    "Numerical argument out of domain", "Result too large", "Resource temporarily unavailable",
+    "Operation now in progress", "Operation already in progress", "Socket operation on non-socket",
+    "Destination address required", "Message too long", "Protocol wrong type for socket",
+    "Protocol not available", "Protocol not supported", "Socket type not supported",
+    "Operation not supported", "Protocol family not supported", "Address family not supported",
+    "Address already in use", "Cannot assign requested address", "Network is down", "Network is unreachable",
+    "Network connection reset", "Connection aborted", "Connection reset by peer", "No buffer space available",
+    "Socket is already connected", "Socket is not connected", "Socket is shut down", "Too many references",
+    "Operation timed out", "Connection refused", "Too many symbolic links", "File name too long",
+    "Host is down", "No route to host", "Directory not empty", "Too many processes", "Too many users",
+    "Disk quota exceeded", "Stale file handle", "Remote path has too many levels", "Invalid RPC structure",
+    "RPC version mismatch", "RPC program unavailable", "Program version mismatch", "Invalid RPC procedure",
+    "No locks available", "Function not implemented", "Inappropriate file type", "Authentication error",
+    "Authentication required", "Identifier removed", "No message of requested type", "Value too large",
+    "Operation canceled", "Invalid byte sequence", "Attribute not found", "Programming error",
+    "Bad message", "Multihop attempted", "Link severed", "Protocol error", "Insufficient capabilities",
+    "Operation not permitted in capability mode", "State not recoverable", "Previous owner died"
+};
+static_assert(sizeof(messages) / sizeof(messages[0]) == 97);
+bool Known(int error) { return error >= 0 && error < 97; }
+}
+
+extern "C" {
+char* APS5_VABI strerror_nid_postfix(int error) {
+    thread_local char buffer[128];
+    const int saved = *__error_nid_postfix();
+    if (Known(error)) std::snprintf(buffer, sizeof(buffer), "%s", messages[error]);
+    else std::snprintf(buffer, sizeof(buffer), "Unknown error: %d", error);
+    *__error_nid_postfix() = Known(error) ? saved : 22;
+    return buffer;
+}
+
+int APS5_VABI strerror_r_nid_postfix(int error, char* buffer, std::size_t length) {
+    const int saved = *__error_nid_postfix();
+    char temporary[128];
+    if (Known(error)) std::snprintf(temporary, sizeof(temporary), "%s", messages[error]);
+    else std::snprintf(temporary, sizeof(temporary), "Unknown error: %d", error);
+    const auto required = std::strlen(temporary) + 1;
+    int result = Known(error) ? 0 : 22;
+    if (!buffer || length < required) result = 34;
+    if (buffer && length) {
+        const auto count = required <= length ? required - 1 : length - 1;
+        std::memcpy(buffer, temporary, count);
+        buffer[count] = '\0';
+    }
+    *__error_nid_postfix() = saved;
+    return result;
+}
+
+void APS5_VABI perror_nid_postfix(const char* prefix) {
+    const int saved = *__error_nid_postfix();
+    char message[128];
+    strerror_r_nid_postfix(saved, message, sizeof(message));
+    if (prefix && *prefix) std::fprintf(stderr, "%s: %s\n", prefix, message);
+    else std::fprintf(stderr, "%s\n", message);
+    *__error_nid_postfix() = saved;
+}
+}
diff --git a/core/libs/tests/GuestErrors.cpp b/core/libs/tests/GuestErrors.cpp
new file mode 100644
index 000000000..453dae221
--- /dev/null
+++ b/core/libs/tests/GuestErrors.cpp
@@ -0,0 +1,37 @@
+#include "prx/libc/include/general/VabiMacros.hpp"
+#include <cstdlib>
+#include <cstring>
+#include <thread>
+
+extern "C" {
+char* APS5_VABI strerror_nid_postfix(int);
+int APS5_VABI strerror_r_nid_postfix(int, char*, std::size_t);
+int* APS5_VABI __error_nid_postfix();
+}
+static void Require(bool value) { if (!value) std::abort(); }
+int main() {
+    *__error_nid_postfix() = 13;
+    Require(std::strcmp(strerror_nid_postfix(35), "Resource temporarily unavailable") == 0);
+    Require(*__error_nid_postfix() == 13);
+    Require(std::strcmp(strerror_nid_postfix(78), "Function not implemented") == 0);
+    char* parent = strerror_nid_postfix(22);
+    std::thread worker([] {
+        Require(std::strcmp(strerror_nid_postfix(45), "Operation not supported") == 0);
+    });
+    worker.join();
+    Require(std::strcmp(parent, "Invalid argument") == 0);
+    char buffer[128];
+    for (int error = 0; error <= 96; ++error) {
+        Require(strerror_r_nid_postfix(error, buffer, sizeof(buffer)) == 0);
+        Require(buffer[0] && std::strstr(buffer, "Unknown") == nullptr);
+    }
+    Require(strerror_r_nid_postfix(-1, buffer, sizeof(buffer)) == 22);
+    Require(std::strstr(buffer, "-1") != nullptr);
+    Require(*__error_nid_postfix() == 13);
+    char sentinel[] = "xyz";
+    Require(strerror_r_nid_postfix(22, sentinel, 1) == 34);
+    Require(sentinel[0] == 0 && sentinel[1] == 'y');
+    sentinel[0] = 'x';
+    Require(strerror_r_nid_postfix(22, sentinel, 0) == 34 && sentinel[0] == 'x');
+    Require(strerror_r_nid_postfix(22, nullptr, 0) == 34);
+}