diff --git a/readme.txt b/readme.txt
index 48a925e78..bc129dd72 100644
--- a/readme.txt
+++ b/readme.txt
@@ -77,6 +77,8 @@ Win32-MinGW            - ChibiOS/RT simulator and demo into a WIN32 process,
 *** 1.3.0 ***
 - FIX: Fixed regression in MinGW demo (bug 2745153)(backported in stable
   branch).
+- FIX: Fixed problem with the timeout constant TIME_IMMEDIATE, added a
+  specific test in the test suite (bug 2755170)(backported in stable branch).
 - NEW: Added a code coverage analysis application under ./tests/coverage.
   Currently the test suite explicitly covers about 74% of the kernel code,
   it is not bad as a starting point.
diff --git a/src/chsem.c b/src/chsem.c
index 21f80c284..085f4014b 100644
--- a/src/chsem.c
+++ b/src/chsem.c
@@ -174,8 +174,10 @@ msg_t chSemWaitTimeoutS(Semaphore *sp, systime_t time) {
   chDbgCheck(sp != NULL, "chSemWaitTimeoutS");
 
   if (--sp->s_cnt < 0) {
-    if (TIME_IMMEDIATE == time)
+    if (TIME_IMMEDIATE == time) {
+      sp->s_cnt++;
       return RDY_TIMEOUT;
+    }
     sem_insert(currp, &sp->s_queue);
     currp->p_wtsemp = sp;
     return chSchGoSleepTimeoutS(PRWTSEM, time);
diff --git a/test/testsem.c b/test/testsem.c
index e6153fa8d..d6e432a36 100644
--- a/test/testsem.c
+++ b/test/testsem.c
@@ -37,7 +37,7 @@ static void sem1_setup(void) {
   chSemInit(&sem1, 0);
 }
 
-static msg_t thread(void *p) {
+static msg_t thread1(void *p) {
 
   chSemWait(&sem1);
   test_emit_token(*(char *)p);
@@ -46,11 +46,11 @@ static msg_t thread(void *p) {
 
 static void sem1_execute(void) {
 
-  threads[0] = chThdCreateStatic(wa[0], WA_SIZE, chThdGetPriority()+5, thread, "A");
-  threads[1] = chThdCreateStatic(wa[1], WA_SIZE, chThdGetPriority()+1, thread, "B");
-  threads[2] = chThdCreateStatic(wa[2], WA_SIZE, chThdGetPriority()+3, thread, "C");
-  threads[3] = chThdCreateStatic(wa[3], WA_SIZE, chThdGetPriority()+4, thread, "D");
-  threads[4] = chThdCreateStatic(wa[4], WA_SIZE, chThdGetPriority()+2, thread, "E");
+  threads[0] = chThdCreateStatic(wa[0], WA_SIZE, chThdGetPriority()+5, thread1, "A");
+  threads[1] = chThdCreateStatic(wa[1], WA_SIZE, chThdGetPriority()+1, thread1, "B");
+  threads[2] = chThdCreateStatic(wa[2], WA_SIZE, chThdGetPriority()+3, thread1, "C");
+  threads[3] = chThdCreateStatic(wa[3], WA_SIZE, chThdGetPriority()+4, thread1, "D");
+  threads[4] = chThdCreateStatic(wa[4], WA_SIZE, chThdGetPriority()+2, thread1, "E");
   chSemSignal(&sem1);
   chSemSignal(&sem1);
   chSemSignal(&sem1);
@@ -82,21 +82,46 @@ static void sem2_setup(void) {
   chSemInit(&sem1, 0);
 }
 
+static msg_t thread2(void *p) {
+
+  chThdSleepMilliseconds(50);
+  chSemSignal(&sem1);
+  return 0;
+}
+
 static void sem2_execute(void) {
   int i;
   systime_t target_time;
   msg_t msg;
 
-  msg= chSemWaitTimeout(&sem1, TIME_IMMEDIATE);
+  /*
+   * Testing special case TIME_IMMEDIATE.
+   */
+  msg = chSemWaitTimeout(&sem1, TIME_IMMEDIATE);
   test_assert(msg == RDY_TIMEOUT, "#1");
+  test_assert(isempty(&sem1.s_queue), "#2");            /* Queue not empty */
+  test_assert(sem1.s_cnt == 0, "#3");                   /* Counter not zero */
 
+  /*
+   * Testing not timeout condition.
+   */
+  threads[0] = chThdCreateStatic(wa[0], WA_SIZE, chThdGetPriority()-1, thread2, "A");
+  msg = chSemWaitTimeout(&sem1, MS2ST(500));
+  test_wait_threads();
+  test_assert(msg == RDY_OK, "#4");
+  test_assert(isempty(&sem1.s_queue), "#5");            /* Queue not empty */
+  test_assert(sem1.s_cnt == 0, "#6");                   /* Counter not zero */
+
+  /*
+   * Testing timeout condition.
+   */
   target_time = chTimeNow() + MS2ST(5 * 500);
   for (i = 0; i < 5; i++) {
     test_emit_token('A' + i);
     msg = chSemWaitTimeout(&sem1, MS2ST(500));
-    test_assert(msg == RDY_TIMEOUT, "#2");
-    test_assert(isempty(&sem1.s_queue), "#3");    /* Queue not empty */
-    test_assert(&sem1.s_cnt != 0, "#4");          /* Counter not zero */
+    test_assert(msg == RDY_TIMEOUT, "#7");
+    test_assert(isempty(&sem1.s_queue), "#8");          /* Queue not empty */
+    test_assert(sem1.s_cnt == 0, "#9");                 /* Counter not zero */
   }
   test_assert_sequence("ABCDE");
   test_assert_time_window(target_time, target_time + ALLOWED_DELAY);