diff --git a/core/libs/prx/libkernel/Pthread/Posix/Mutex.cpp b/core/libs/prx/libkernel/Pthread/Posix/Mutex.cpp
index ee0695d43..7ab97118f 100644
--- a/core/libs/prx/libkernel/Pthread/Posix/Mutex.cpp
+++ b/core/libs/prx/libkernel/Pthread/Posix/Mutex.cpp
@@ -6,14 +6,13 @@
 #include "../include/Mutex.hpp"
 #include "Common.hpp"
 #include <atomic>
-#include <chrono>
-#include <limits>
 #include <stdexcept>
 #include <string>
 
 namespace {
 
 constexpr int POSIX_EINVAL = 22;
+constexpr int GUEST_REALTIME_CLOCK = 0;
 constexpr int POSIX_PRIO_PROTECT = 2;
 constexpr int POSIX_SCHED_RR = 3;
 constexpr std::uintptr_t POSIX_ADAPTIVE_MUTEX_INITIALIZER = 1;
@@ -62,12 +61,10 @@ int APS5_VABI pthread_mutex_lock_nid_postfix(PthreadMutex* mutex) {
 
 int APS5_VABI pthread_mutex_timedlock_nid_postfix(PthreadMutex* mutex, const KernelTimespec* abstime) {
     if (!abstime) throw std::runtime_error("pthread_mutex_timedlock: null abstime");
-    if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) return POSIX_EINVAL;
     _initializeStatic(mutex, __func__);
-    const auto deadline = std::chrono::seconds(abstime->tv_sec) + std::chrono::nanoseconds(abstime->tv_nsec);
-    const auto now = std::chrono::system_clock::now().time_since_epoch();
-    const auto remaining = std::chrono::duration_cast<std::chrono::microseconds>(deadline - now).count();
-    const auto usec = remaining <= 0 ? 0 : remaining >= std::numeric_limits<KernelUseconds>::max() ? std::numeric_limits<KernelUseconds>::max() : static_cast<KernelUseconds>(remaining);
+    if (scePthreadMutexTrylock(mutex) == 0) return 0;
+    KernelUseconds usec = 0;
+    if (!PosixThread::RelativeMicroseconds(GUEST_REALTIME_CLOCK, abstime, &usec)) return POSIX_EINVAL;
     return PosixThread::ToErrno(scePthreadMutexTimedlock(mutex, usec));
 }
 
diff --git a/core/libs/tests/GuestPthreadMutexattr.cpp b/core/libs/tests/GuestPthreadMutexattr.cpp
index 410fb354e..410aa02ba 100644
--- a/core/libs/tests/GuestPthreadMutexattr.cpp
+++ b/core/libs/tests/GuestPthreadMutexattr.cpp
@@ -1,4 +1,5 @@
 #include "SceTypes.hpp"
+#include <cstdint>
 #include <cstdlib>
 #include <stdexcept>
 
@@ -14,6 +15,9 @@ int APS5_VABI pthread_mutex_init_nid_postfix(PthreadMutex* mutex, const PthreadM
 int APS5_VABI pthread_mutex_lock_nid_postfix(PthreadMutex* mutex);
 int APS5_VABI pthread_mutex_unlock_nid_postfix(PthreadMutex* mutex);
 int APS5_VABI pthread_mutex_destroy_nid_postfix(PthreadMutex* mutex);
+int APS5_VABI pthread_mutex_timedlock_nid_postfix(PthreadMutex* mutex, const KernelTimespec* abstime);
+int APS5_VABI scePthreadCreate(Pthread* thread, const PthreadAttr* attr, PthreadEntry entry, void* arg, const char* name);
+int APS5_VABI scePthreadJoin(Pthread thread, void** retval);
 int APS5_VABI sched_get_priority_max_nid_postfix(int policy);
 }
 
@@ -35,6 +39,25 @@ static bool Throws(Call call) {
     return false;
 }
 
+static constexpr KernelTimespec INVALID_DEADLINE{0, 1000000000};
+
+static void* APS5_VABI TimedlockInvalidDeadline(void* arg) {
+    auto* mutex = static_cast<PthreadMutex*>(arg);
+    return reinterpret_cast<void*>(static_cast<std::intptr_t>(pthread_mutex_timedlock_nid_postfix(mutex, &INVALID_DEADLINE)));
+}
+
+static void CheckTimedlockInvalidDeadline() {
+    PthreadMutex mutex = nullptr;
+    Require(pthread_mutex_init_nid_postfix(&mutex, nullptr) == 0);
+    Require(pthread_mutex_timedlock_nid_postfix(&mutex, &INVALID_DEADLINE) == 0);
+    Pthread thread{};
+    void* result = nullptr;
+    Require(scePthreadCreate(&thread, nullptr, TimedlockInvalidDeadline, &mutex, nullptr) == 0);
+    Require(scePthreadJoin(thread, &result) == 0 && reinterpret_cast<std::intptr_t>(result) == GUEST_EINVAL);
+    Require(pthread_mutex_unlock_nid_postfix(&mutex) == 0);
+    Require(pthread_mutex_destroy_nid_postfix(&mutex) == 0);
+}
+
 static void CheckType() {
     PthreadMutexattr attr = nullptr;
     Require(pthread_mutexattr_init_nid_postfix(&attr) == 0);
@@ -55,6 +78,7 @@ static void CheckType() {
 
 int main() {
     CheckType();
+    CheckTimedlockInvalidDeadline();
     PthreadMutexattr attr = nullptr;
     Require(pthread_mutexattr_init_nid_postfix(&attr) == 0);
     int ceiling = -1;