diff --git a/core/libs/prx/libkernel/File/src/Stdio.cpp b/core/libs/prx/libkernel/File/src/Stdio.cpp
index 4d597c117..fa2d30cfc 100644
--- a/core/libs/prx/libkernel/File/src/Stdio.cpp
+++ b/core/libs/prx/libkernel/File/src/Stdio.cpp
@@ -14,6 +14,7 @@
 #include <cstring>
 #include <cstdarg>
 #include <filesystem>
+#include <optional>
 #include <stdexcept>
 #include <string>
 #ifdef _WIN32
@@ -32,6 +33,30 @@ static int NativeMkdir(const std::filesystem::path& path, std::uint16_t mode) {
 static int NativeChmod(const std::filesystem::path& path, int mode) {
     return ::_wchmod(path.wstring().c_str(), mode);
 }
+static std::optional<std::filesystem::path> NativeDescriptorPath(int descriptor) {
+    if (auto directory = File::DirectoryDescriptorPath(descriptor)) return directory;
+    const auto handle = reinterpret_cast<HANDLE>(::_get_osfhandle(descriptor));
+    if (handle == INVALID_HANDLE_VALUE) {
+        errno = EBADF;
+        return std::nullopt;
+    }
+    std::wstring path(MAX_PATH, L'\0');
+    auto length = ::GetFinalPathNameByHandleW(handle, path.data(), static_cast<DWORD>(path.size()), FILE_NAME_NORMALIZED);
+    if (length >= path.size()) {
+        path.resize(length);
+        length = ::GetFinalPathNameByHandleW(handle, path.data(), length, FILE_NAME_NORMALIZED);
+    }
+    if (length == 0 || length >= path.size()) {
+        errno = EINVAL;
+        return std::nullopt;
+    }
+    path.resize(length);
+    return path;
+}
+static int NativeFchmod(int descriptor, int mode) {
+    const auto path = NativeDescriptorPath(descriptor);
+    return path ? NativeChmod(*path, mode) : -1;
+}
 static int NativeFtruncate(int descriptor, std::int64_t length) {
     return static_cast<int>(::_chsize_s(descriptor, length));
 }
@@ -99,6 +124,9 @@ static int NativeMkdir(const std::filesystem::path& path, std::uint16_t mode) {
 static int NativeChmod(const std::filesystem::path& path, int mode) {
     return ::chmod(path.c_str(), static_cast<mode_t>(mode));
 }
+static int NativeFchmod(int descriptor, int mode) {
+    return ::fchmod(descriptor, static_cast<mode_t>(mode));
+}
 static int NativeFtruncate(int descriptor, std::int64_t length) {
     return ::ftruncate(descriptor, static_cast<off_t>(length));
 }
@@ -121,6 +149,7 @@ static std::int64_t NativePwrite(int descriptor, const void* buf, std::size_t nb
 
 static constexpr int GUEST_ENOENT = 2;
 static constexpr int GUEST_EIO = 5;
+static constexpr int GUEST_EBADF = 9;
 static constexpr int GUEST_EFAULT = 14;
 static constexpr int GUEST_EEXIST = 17;
 static constexpr int GUEST_EINVAL = 22;
@@ -469,6 +498,16 @@ int APS5_VABI sceKernelChmod_nid_postfix(const char* path, std::uint16_t mode) {
     return chmod_nid_postfix(path, mode);
 }
 
+int APS5_VABI sceKernelFchmod(int d, std::uint16_t mode) {
+    if (d >= GuestSockets::FirstDescriptor) return SceErrorFromErrno(GuestSockets::IsOpen(d) ? GUEST_EINVAL : GUEST_EBADF);
+    if (NativeFchmod(d, mode & 07777) != 0) return SceErrorFromErrno(errno);
+    return 0;
+}
+
+int APS5_VABI fchmod_nid_postfix(int d, int mode) {
+    return PosixResult(sceKernelFchmod(d, static_cast<std::uint16_t>(mode)));
+}
+
 int APS5_VABI sceKernelTruncate_nid_postfix(const char* path, std::int64_t length) {
     if (path == nullptr) throw std::invalid_argument("sceKernelTruncate: path is null");
     if (length < 0) return SceErrorFromErrno(GUEST_EINVAL);
diff --git a/core/libs/prx/libkernel/Socket/include/SocketRuntime.hpp b/core/libs/prx/libkernel/Socket/include/SocketRuntime.hpp
index ee0899030..0ef89de10 100644
--- a/core/libs/prx/libkernel/Socket/include/SocketRuntime.hpp
+++ b/core/libs/prx/libkernel/Socket/include/SocketRuntime.hpp
@@ -2,4 +2,5 @@
 namespace GuestSockets {
 constexpr int FirstDescriptor = 0x10000000;
 int Close(int descriptor);
+bool IsOpen(int descriptor);
 }
diff --git a/core/libs/prx/libkernel/Socket/src/Udp.cpp b/core/libs/prx/libkernel/Socket/src/Udp.cpp
index bffca9598..ee5931b22 100644
--- a/core/libs/prx/libkernel/Socket/src/Udp.cpp
+++ b/core/libs/prx/libkernel/Socket/src/Udp.cpp
@@ -158,6 +158,11 @@ int GuestSockets::Close(int descriptor) {
     return sockets.erase(descriptor) ? 0 : Fail(9);
 }
 
+bool GuestSockets::IsOpen(int descriptor) {
+    std::lock_guard lock(socketsMutex);
+    return sockets.contains(descriptor);
+}
+
 extern "C" {
 int APS5_VABI fcntl_nid_postfix(int descriptor, int command, ...) {
     const auto socket = Lookup(descriptor);
diff --git a/core/libs/prx/libkernel/Unimplemented.cpp b/core/libs/prx/libkernel/Unimplemented.cpp
index 6c5ee71eb..fd6b61a57 100644
--- a/core/libs/prx/libkernel/Unimplemented.cpp
+++ b/core/libs/prx/libkernel/Unimplemented.cpp
@@ -27,16 +27,6 @@ int APS5_VABI pthread_cancel_nid_postfix(void) {
     NotImplemented_nid_no_patch("0D4-FVvEikw");
     return 0;
 }
-int APS5_VABI sceKernelFchmod(void) {
-    NotImplemented_nid_no_patch(__func__);
-    return 0;
-}
-
-int APS5_VABI fchmod_nid_postfix(void) {
-    NotImplemented_nid_no_patch(__func__);
-    return 0;
-}
-
 int APS5_VABI futimes_nid_postfix(void) {
     NotImplemented_nid_no_patch(__func__);
     return 0;
diff --git a/core/libs/tests/GuestFilesystem.cpp b/core/libs/tests/GuestFilesystem.cpp
index d99ae96d3..9f17aa3e1 100644
--- a/core/libs/tests/GuestFilesystem.cpp
+++ b/core/libs/tests/GuestFilesystem.cpp
@@ -9,6 +9,9 @@ extern "C" {
 int APS5_VABI remove_nid_postfix(const char*);
 int APS5_VABI rename_nid_postfix(const char*, const char*);
 int APS5_VABI sceKernelChmod_nid_postfix(const char*, unsigned short);
+int APS5_VABI sceKernelFchmod(int, unsigned short);
+int APS5_VABI fchmod_nid_postfix(int, int);
+int APS5_VABI socket_nid_postfix(int, int, int);
 int APS5_VABI sceKernelFsync(int);
 int APS5_VABI sceKernelFtruncate(int, long long);
 int APS5_VABI sceKernelTruncate_nid_postfix(const char*, long long);
@@ -74,9 +77,24 @@ int main() {
     const int descriptor = ::fileno(native);
 #endif
     Require(descriptor >= 0 && sceKernelFsync(descriptor) == 0);
+    const auto ownerWrite = [&] {
+        return (std::filesystem::status(sized).permissions() & std::filesystem::perms::owner_write) != std::filesystem::perms::none;
+    };
+    Require(sceKernelFchmod(descriptor, 0400) == 0 && !ownerWrite());
+    Require(fchmod_nid_postfix(descriptor, 0600) == 0 && ownerWrite());
     Require(sceKernelFtruncate(descriptor, 3) == 0);
     Require(std::fclose(native) == 0);
     Require(std::filesystem::file_size(sized) == 3);
+#ifndef _WIN32
+    Require(sceKernelFchmod(descriptor, 0600) == static_cast<int>(0x80020009u));
+    Require(fchmod_nid_postfix(descriptor, 0600) == -1 && *__error_nid_postfix() == 9);
+#endif
+    const int socket = socket_nid_postfix(2, 2, 0);
+    Require(socket >= 0);
+    Require(sceKernelFchmod(socket, 0600) == static_cast<int>(0x80020016u));
+    Require(fchmod_nid_postfix(socket, 0600) == -1 && *__error_nid_postfix() == 22);
+    Require(close_nid_postfix(socket) == 0);
+    Require(fchmod_nid_postfix(socket, 0600) == -1 && *__error_nid_postfix() == 9);
     Require(remove_nid_postfix(sized.string().c_str()) == 0);
     const auto present = root / "present.txt";
     const auto presentName = present.string();