diff --git a/win32/devdoc/threadpool_win32.md b/win32/devdoc/threadpool_win32.md
index b0be6739..f6baca03 100644
--- a/win32/devdoc/threadpool_win32.md
+++ b/win32/devdoc/threadpool_win32.md
@@ -215,7 +215,7 @@ MOCKABLE_FUNCTION(, int, threadpool_timer_restart, TIMER_INSTANCE_HANDLE, timer,
 
 **SRS_THREADPOOL_WIN32_42_019: [** If `timer` is `NULL`, `threadpool_timer_restart` shall fail and return a non-zero value. **]**
 
-If timer state is `DESTROYING`, `threadpool_timer_restart` shall fail and return a non-zero value.
+**SRS_THREADPOOL_WIN32_07_001: [** If timer state is in destroying state, `threadpool_timer_restart` shall fail and return a non-zero value. **]**
 
 **SRS_THREADPOOL_WIN32_42_022: [** `threadpool_timer_restart` shall call `SetThreadpoolTimer`, passing negative `start_delay_ms` as `pftDueTime`, `timer_period_ms` as `msPeriod`, and 0 as `msWindowLength`. **]**
 
@@ -245,7 +245,7 @@ MOCKABLE_FUNCTION(, void, threadpool_timer_destroy, TIMER_INSTANCE_HANDLE, timer
 
 **SRS_THREADPOOL_WIN32_42_011: [** If `timer` is `NULL`, `threadpool_timer_destroy` shall fail and return. **]**
 
-`threadpool_timer_destroy` shall switch the state to `DESTROYING`.
+**SRS_THREADPOOL_WIN32_07_002: [** `threadpool_timer_destroy` shall indicate the timer is in destroying state. **]**
 
 **SRS_THREADPOOL_WIN32_42_012: [** `threadpool_timer_destroy` shall call `SetThreadpoolTimer` with `NULL` for `pftDueTime` and 0 for `msPeriod` and `msWindowLength` to cancel ongoing timers. **]**
 
@@ -253,7 +253,7 @@ MOCKABLE_FUNCTION(, void, threadpool_timer_destroy, TIMER_INSTANCE_HANDLE, timer
 
 **SRS_THREADPOOL_WIN32_42_014: [** `threadpool_timer_destroy` shall call `CloseThreadpoolTimer`. **]**
 
-`threadpool_timer_destroy` shall switch the state to `DESTROYED`.
+**SRS_THREADPOOL_WIN32_07_003: [** `threadpool_timer_destroy` shall indicate the timer is destroyed. **]**
 
 **SRS_THREADPOOL_WIN32_42_015: [** `threadpool_timer_destroy` shall free all resources in `timer`. **]**
 
diff --git a/win32/src/threadpool_win32.c b/win32/src/threadpool_win32.c
index 855a522e..cc1c28b8 100644
--- a/win32/src/threadpool_win32.c
+++ b/win32/src/threadpool_win32.c
@@ -42,6 +42,7 @@ typedef struct TIMER_INSTANCE_TAG
     PTP_TIMER timer;
     THREADPOOL_WORK_FUNCTION work_function;
     void* work_function_context;
+    volatile_atomic int32_t is_destroying;
 } TIMER_INSTANCE;
 
 typedef struct THREADPOOL_TAG
@@ -583,6 +584,7 @@ int threadpool_timer_start(THANDLE(THREADPOOL) threadpool, uint32_t start_delay_
                 }
                 else
                 {
+                    (void)interlocked_exchange(&timer_temp->is_destroying, 0);
                     timer_temp->timer = tp_timer;
                     timer_temp->work_function = work_function;
                     timer_temp->work_function_context = work_function_context;
@@ -625,6 +627,14 @@ int threadpool_timer_restart(TIMER_INSTANCE_HANDLE timer, uint32_t start_delay_m
             timer, start_delay_ms, timer_period_ms);
         result = MU_FAILURE;
     }
+    else if(
+        /* Codes_SRS_THREADPOOL_WIN32_07_001: [ If timer state is in destroying state, threadpool_timer_restart shall fail and return a non - zero value. ]*/
+        interlocked_add(&timer->is_destroying, 0) == 1
+        )
+    {
+        LogError("timer is in closing state");
+        result = MU_FAILURE;
+    }
     else
     {
         /* Codes_SRS_THREADPOOL_WIN32_42_022: [ threadpool_timer_restart shall call SetThreadpoolTimer, passing negative start_delay_ms as pftDueTime, timer_period_ms as msPeriod, and 0 as msWindowLength. ]*/
@@ -661,6 +671,8 @@ void threadpool_timer_destroy(TIMER_INSTANCE_HANDLE timer)
     }
     else
     {
+        /* Codes_SRS_THREADPOOL_WIN32_07_002: [ threadpool_timer_destroy shall indicate the timer is in destroying state. ]*/
+        (void)interlocked_exchange(&timer->is_destroying, 1);
         /* Codes_SRS_THREADPOOL_WIN32_42_012: [ threadpool_timer_destroy shall call SetThreadpoolTimer with NULL for pftDueTime and 0 for msPeriod and msWindowLength to cancel ongoing timers. ]*/
         /* Codes_SRS_THREADPOOL_WIN32_42_013: [ threadpool_timer_destroy shall call WaitForThreadpoolTimerCallbacks. ]*/
         threadpool_internal_cancel_timer_and_wait(timer->timer);
@@ -670,5 +682,8 @@ void threadpool_timer_destroy(TIMER_INSTANCE_HANDLE timer)
 
         /* Codes_SRS_THREADPOOL_WIN32_42_015: [ threadpool_timer_destroy shall free all resources in timer. ]*/
         free(timer);
+
+        /* Codes_SRS_THREADPOOL_WIN32_07_003: [ threadpool_timer_destroy shall indicate the timer is destroyed. ]*/
+        (void)interlocked_exchange(&timer->is_destroying, 0);
     }
 }
diff --git a/win32/tests/threadpool_win32_ut/threadpool_win32_ut.c b/win32/tests/threadpool_win32_ut/threadpool_win32_ut.c
index 0e4cf4e8..a98540b6 100644
--- a/win32/tests/threadpool_win32_ut/threadpool_win32_ut.c
+++ b/win32/tests/threadpool_win32_ut/threadpool_win32_ut.c
@@ -990,6 +990,7 @@ TEST_FUNCTION(threadpool_timer_start_succeeds)
         .CaptureArgumentValue_pfnti(&test_timer_callback)
         .CaptureArgumentValue_pv(&test_timer_callback_context)
         .CaptureReturn(&ptp_timer);
+    STRICT_EXPECTED_CALL(interlocked_exchange(IGNORED_ARG, 0));
     STRICT_EXPECTED_CALL(mocked_SetThreadpoolTimer(IGNORED_ARG, &filetime_expected, 2000, 0))
         .ValidateArgumentValue_pti(&ptp_timer);
 
@@ -1030,6 +1031,7 @@ TEST_FUNCTION(threadpool_timer_start_with_NULL_work_function_context_succeeds)
         .CaptureArgumentValue_pfnti(&test_timer_callback)
         .CaptureArgumentValue_pv(&test_timer_callback_context)
         .CaptureReturn(&ptp_timer);
+    STRICT_EXPECTED_CALL(interlocked_exchange(IGNORED_ARG, 0));
     STRICT_EXPECTED_CALL(mocked_SetThreadpoolTimer(IGNORED_ARG, &filetime_expected, 2000, 0))
         .ValidateArgumentValue_pti(&ptp_timer);
 
@@ -1110,6 +1112,27 @@ TEST_FUNCTION(threadpool_timer_restart_with_NULL_timer_fails)
     ASSERT_ARE_NOT_EQUAL(int, 0, result);
 }
 
+/* Tests_SRS_THREADPOOL_WIN32_07_001: [ If timer state is in destroying state, threadpool_timer_restart shall fail and return a non - zero value. ]*/
+TEST_FUNCTION(threadpool_timer_restart_with_timer_is_closing_fails)
+{
+    // arrange
+    THANDLE(THREADPOOL) threadpool = NULL;
+    PTP_TIMER_CALLBACK test_timer_callback;
+    PVOID test_timer_callback_context;
+    PTP_TIMER ptp_timer;
+    TIMER_INSTANCE_HANDLE timer_instance;
+    test_create_threadpool_and_start_timer(42, 2000, (void*)0x4243, &threadpool, &ptp_timer, &test_timer_callback, &test_timer_callback_context, &timer_instance);
+
+    STRICT_EXPECTED_CALL(interlocked_add(IGNORED_ARG, 0)).SetReturn(1);
+
+    // act
+    int result = threadpool_timer_restart(timer_instance, 43, 1000);
+
+    // assert
+    ASSERT_ARE_EQUAL(char_ptr, umock_c_get_expected_calls(), umock_c_get_actual_calls());
+    ASSERT_ARE_NOT_EQUAL(int, 0, result);
+}
+
 /* Tests_SRS_THREADPOOL_WIN32_42_022: [ threadpool_timer_restart shall call SetThreadpoolTimer, passing negative start_delay_ms as pftDueTime, timer_period_ms as msPeriod, and 0 as msWindowLength. ]*/
 /* Tests_SRS_THREADPOOL_WIN32_42_023: [ threadpool_timer_restart shall succeed and return 0. ]*/
 TEST_FUNCTION(threadpool_timer_restart_succeeds)
@@ -1128,6 +1151,7 @@ TEST_FUNCTION(threadpool_timer_restart_succeeds)
     filetime_expected.dwHighDateTime = ularge_due_time.HighPart;
     filetime_expected.dwLowDateTime = ularge_due_time.LowPart;
 
+    STRICT_EXPECTED_CALL(interlocked_add(IGNORED_ARG, 0));
     STRICT_EXPECTED_CALL(mocked_SetThreadpoolTimer(IGNORED_ARG, &filetime_expected, 1000, 0))
         .ValidateArgumentValue_pti(&ptp_timer);
 
@@ -1201,6 +1225,8 @@ TEST_FUNCTION(threadpool_timer_destroy_with_NULL_timer_fails)
 /* Tests_SRS_THREADPOOL_WIN32_42_013: [ threadpool_timer_destroy shall call WaitForThreadpoolTimerCallbacks. ]*/
 /* Tests_SRS_THREADPOOL_WIN32_42_014: [ threadpool_timer_destroy shall call CloseThreadpoolTimer. ]*/
 /* Tests_SRS_THREADPOOL_WIN32_42_015: [ threadpool_timer_destroy shall free all resources in timer. ]*/
+/* Tests_SRS_THREADPOOL_WIN32_07_002: [ threadpool_timer_destroy shall indicate the timer is in destroying state. ]*/
+/* Tests_SRS_THREADPOOL_WIN32_07_003: [ threadpool_timer_destroy shall indicate the timer is destroyed. ]*/
 TEST_FUNCTION(threadpool_timer_destroy_succeeds)
 {
     // arrange
@@ -1211,10 +1237,12 @@ TEST_FUNCTION(threadpool_timer_destroy_succeeds)
     TIMER_INSTANCE_HANDLE timer_instance;
     test_create_threadpool_and_start_timer(42, 2000, (void*)0x4243, &threadpool, &ptp_timer, &test_timer_callback, &test_timer_callback_context, &timer_instance);
 
+    STRICT_EXPECTED_CALL(interlocked_exchange(IGNORED_ARG, 1));
     STRICT_EXPECTED_CALL(mocked_SetThreadpoolTimer(ptp_timer, NULL, 0, 0));
     STRICT_EXPECTED_CALL(mocked_WaitForThreadpoolTimerCallbacks(ptp_timer, TRUE));
     STRICT_EXPECTED_CALL(mocked_CloseThreadpoolTimer(ptp_timer));
     STRICT_EXPECTED_CALL(free(IGNORED_ARG));
+    STRICT_EXPECTED_CALL(interlocked_exchange(IGNORED_ARG, 0));
 
     // act
     threadpool_timer_destroy(timer_instance);