diff --git a/core/libs/prx/libkernel/CMakeLists.txt b/core/libs/prx/libkernel/CMakeLists.txt
index 31ad9ae4b..752f3f7e8 100644
--- a/core/libs/prx/libkernel/CMakeLists.txt
+++ b/core/libs/prx/libkernel/CMakeLists.txt
@@ -84,6 +84,16 @@ if(BUILD_TESTING)
         set_tests_properties(guest_posix_sem_init guest_posix_sem_post PROPERTIES ENVIRONMENT_MODIFICATION
             "PATH=path_list_prepend:$<TARGET_FILE_DIR:libkernel>")
     endif()
+    add_test_executable(guest_process_time_tests ${LIBS_INCLUDE_DIR}/tests/GuestProcessTime.cpp)
+    target_include_directories(guest_process_time_tests PRIVATE ${LIBS_INCLUDE_DIR})
+    target_link_libraries(guest_process_time_tests PRIVATE libkernel libc)
+    configure_windows_unwind(guest_process_time_tests)
+    add_test(NAME guest_process_time COMMAND guest_process_time_tests)
+    add_test(NAME guest_process_time_counter COMMAND guest_process_time_tests counter)
+    if(WIN32)
+        set_tests_properties(guest_process_time guest_process_time_counter PROPERTIES ENVIRONMENT_MODIFICATION
+            "PATH=path_list_prepend:$<TARGET_FILE_DIR:libkernel>")
+    endif()
     add_library(guest_module_fixture SHARED ${LIBS_INCLUDE_DIR}/tests/GuestModuleFixture.cpp)
     target_include_directories(guest_module_fixture PRIVATE ${LIBS_INCLUDE_DIR})
     add_custom_command(TARGET guest_module_fixture POST_BUILD
diff --git a/core/libs/prx/libkernel/Time/Time.cpp b/core/libs/prx/libkernel/Time/Time.cpp
index 395f85829..521328a18 100644
--- a/core/libs/prx/libkernel/Time/Time.cpp
+++ b/core/libs/prx/libkernel/Time/Time.cpp
@@ -147,11 +147,13 @@ static const bool g_timerSelfTest = [] {
 extern "C" {
 
 std::uint64_t APS5_VABI sceKernelGetProcessTime() {
-    return (GetMonotonicNanos() - GetStartNanos()) / 1000ULL;
+    const std::uint64_t start = GetStartNanos();
+    return (GetMonotonicNanos() - start) / 1000ULL;
 }
 
 std::uint64_t APS5_VABI sceKernelGetProcessTimeCounter() {
-    return GetMonotonicNanos() - GetStartNanos();
+    const std::uint64_t start = GetStartNanos();
+    return GetMonotonicNanos() - start;
 }
 
 std::uint64_t APS5_VABI sceKernelGetProcessTimeCounterFrequency() {
diff --git a/core/libs/tests/GuestProcessTime.cpp b/core/libs/tests/GuestProcessTime.cpp
new file mode 100644
index 000000000..b24cf8249
--- /dev/null
+++ b/core/libs/tests/GuestProcessTime.cpp
@@ -0,0 +1,24 @@
+#include "prx/libkernel/Time/include/Time.hpp"
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+static void Require(bool condition, const char* message) {
+    if (!condition) {
+        std::fprintf(stderr, "%s\n", message);
+        std::abort();
+    }
+}
+
+int main(int argc, char** argv) {
+    constexpr std::uint64_t minuteMicros = 60ULL * 1000 * 1000;
+    if (argc > 1 && std::strcmp(argv[1], "counter") == 0) {
+        Require(sceKernelGetProcessTimeCounter() < minuteMicros * 1000, "first process time counter wrapped");
+        return 0;
+    }
+    const std::uint64_t first = sceKernelGetProcessTime();
+    Require(first < minuteMicros, "first process time wrapped");
+    Require(sceKernelGetProcessTime() >= first, "process time went backwards");
+    return 0;
+}