diff --git a/src/fsfw/osal/rtems/Clock.cpp b/src/fsfw/osal/rtems/Clock.cpp
index cb7bd0429..1ffed9871 100644
--- a/src/fsfw/osal/rtems/Clock.cpp
+++ b/src/fsfw/osal/rtems/Clock.cpp
@@ -107,9 +107,6 @@ ReturnValue_t Clock::getDateAndTime(TimeOfDay_t* time) {
   rtems_status_code status = rtems_clock_get_tod(&timeRtems);
   switch (status) {
     case RTEMS_SUCCESSFUL: {
-      /* The last field now contains the RTEMS ticks of the seconds from 0
-      to rtems_clock_get_ticks_per_second() minus one.
-      We calculate the microseconds accordingly */
       time->day = timeRtems.day;
       time->hour = timeRtems.hour;
       time->minute = timeRtems.minute;
@@ -140,7 +137,7 @@ ReturnValue_t Clock::convertTimeOfDayToTimeval(const TimeOfDay_t* from, timeval*
   timeRtems.hour = from->hour;
   timeRtems.minute = from->minute;
   timeRtems.second = from->second;
-  timeRtems.ticks = from->usecond * getTicksPerSecond() / 1e6;
+  timeRtems.ticks = from->usecond * rtems_clock_get_ticks_per_second() / 1e6;
   to->tv_sec = _TOD_To_seconds(&timeRtems);
   to->tv_usec = from->usecond;
   return returnvalue::OK;
diff --git a/unittests/CMakeLists.txt b/unittests/CMakeLists.txt
index ad26e3923..e02e76494 100644
--- a/unittests/CMakeLists.txt
+++ b/unittests/CMakeLists.txt
@@ -20,7 +20,9 @@ add_subdirectory(globalfunctions)
 add_subdirectory(timemanager)
 add_subdirectory(tmtcpacket)
 add_subdirectory(cfdp)
+IF(NOT FSFW_OSAL MATCHES "rtems")
 add_subdirectory(hal)
+ENDIF()
 add_subdirectory(internalerror)
 add_subdirectory(devicehandler)
 add_subdirectory(tmtcservices)
diff --git a/unittests/CatchRunner.cpp b/unittests/CatchRunner.cpp
index b6017b430..59dde71ec 100644
--- a/unittests/CatchRunner.cpp
+++ b/unittests/CatchRunner.cpp
@@ -46,38 +46,53 @@ void unittestTaskFunction(void* pvParameters) {
 #ifdef FSFW_OSAL_RTEMS
 #include <signal.h>
 
-int sigaltstack(const stack_t * ss, stack_t * old_ss){
-  return 0;
-}
+int sigaltstack(const stack_t* ss, stack_t* old_ss) { return 0; }
 extern "C" {
 
-#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
-#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
+void exit_qemu_failing(int error) {
+  asm(/* 0x20026 == ADP_Stopped_ApplicationExit */
+         "mov x1, #0x26\n\t"
+        "movk x1, #2, lsl #16\n\t"
+        "str x1, [sp,#0]\n\t");
 
-#define CONFIGURE_UNLIMITED_OBJECTS
-#define CONFIGURE_UNIFIED_WORK_AREAS
+    /* Exit status code. Host QEMU process exits with that status. */
+    asm("mov x0, %[error]\n\t" : : [error] "r" (error));
+    asm(
+        "str x0, [sp,#8]\n\t"
 
-#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
+    /* x1 contains the address of parameter block.
+     * Any memory address could be used. */
+        "mov x1, sp\n\t"
 
-#define CONFIGURE_INIT
+    /* SYS_EXIT */
+        "mov w0, #0x18\n\t"
 
-#include <rtems/confdefs.h>
-
-
-#include <rtems.h>
-#include <stdlib.h>
-#include <stdio.h>
-
-rtems_task Init(
-  rtems_task_argument ignored
-)
-{
-  printf( "\nHello World\n" );
-  char* argv[] = {"fsfw-test"};
-  int result = Catch::Session().run(1, argv);
-  exit( result );
+    /* Do the semihosting call on A64. */
+        "hlt 0xf000\n\t"
+);
 }
 
+#include "testcfg/rtems/rtemsConfig.h"
+
+rtems_task Init(rtems_task_argument ignored) {
+  rtems_time_of_day now;
+  now.year = 2023;
+  now.month = 1;
+  now.day = 15;
+  now.hour = 0;
+  now.minute = 0;
+  now.second = 0;
+  now.ticks = 0;
+  rtems_clock_set(&now);
+  customSetup();
+  const char* argv[] = {"fsfw-test", ""};
+  int result = Catch::Session().run(1, argv);
+  customTeardown();
+  if (result != 0) {
+    exit_qemu_failing(result);
+  }
+  exit(result);
+}
 }
 #endif
 
diff --git a/unittests/osal/TestClock.cpp b/unittests/osal/TestClock.cpp
index bdfefde63..5e381e8bf 100644
--- a/unittests/osal/TestClock.cpp
+++ b/unittests/osal/TestClock.cpp
@@ -8,6 +8,8 @@
 
 #include "CatchDefinitions.h"
 
+//TODO setClock()
+
 TEST_CASE("OSAL::Clock Test", "[OSAL::Clock Test]") {
   SECTION("Test getClock") {
     timeval time;
@@ -22,7 +24,14 @@ TEST_CASE("OSAL::Clock Test", "[OSAL::Clock Test]") {
     // We require timeOfDayAsTimeval to be larger than time as it
     // was request a few ns later
     double difference = timevalOperations::toDouble(timeOfDayAsTimeval - time);
-    CHECK(difference >= 0.0);
+    uint32_t ticksPerSecond =Clock:: getTicksPerSecond();
+    float secondPerTick = 0;
+    if (ticksPerSecond != 0){
+      secondPerTick = 1.0 / ticksPerSecond;
+    }
+    // In rtems, timevals have microsecond resolution, while TOD has only tick resolution, leading to
+    // negative differences when comparing "equal" times
+    CHECK(difference >= -secondPerTick);
     CHECK(difference <= 0.005);
 
     // Conversion in the other direction
diff --git a/unittests/testcfg/rtems/rtemsConfig.h b/unittests/testcfg/rtems/rtemsConfig.h
new file mode 100644
index 000000000..e9af11079
--- /dev/null
+++ b/unittests/testcfg/rtems/rtemsConfig.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#define RTEMS_USE_UNLIMITED_OBJECTS_ALLOCATION 0
+
+#define CONFIGURE_MICROSECONDS_PER_TICK 1000
+
+#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
+
+#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
+#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
+
+#define CONFIGURE_MAXIMUM_TASKS 20
+#define CONFIGURE_MAXIMUM_MESSAGE_QUEUES 30
+#define CONFIGURE_MAXIMUM_SEMAPHORES 20
+#define CONFIGURE_MAXIMUM_TIMERS 10
+//! Required for Rate-Monotonic Scheduling (RMS)
+#define CONFIGURE_MAXIMUM_PERIODS 15
+#define CONFIGURE_INIT_TASK_STACK_SIZE (RTEMS_MINIMUM_STACK_SIZE * 6)
+//! Around 41 kB extra task stack for now.
+#define CONFIGURE_EXTRA_TASK_STACKS (10 * RTEMS_MINIMUM_STACK_SIZE)
+
+#define CONFIGURE_INIT
+
+#include <rtems.h>
+#include <rtems/confdefs.h>