diff --git a/src/timer.cpp b/src/timer.cpp
index 965d77c4..2cf83a9a 100644
--- a/src/timer.cpp
+++ b/src/timer.cpp
@@ -3,7 +3,7 @@
 
 #include "global.hpp"
 
-void _app_timer_create (HWND hwnd, const MFILTER_APPS* ptr_apps, time_t seconds)
+void _app_timer_create (HWND hwnd, const MFILTER_APPS *ptr_apps, time_t seconds)
 {
 	if (!config.hengine || !ptr_apps || ptr_apps->empty ())
 		return;
@@ -19,8 +19,8 @@ void _app_timer_create (HWND hwnd, const MFILTER_APPS* ptr_apps, time_t seconds)
 
 		if (ptr_app->htimer)
 		{
-			DeleteTimerQueueTimer (config.htimer, ptr_app->htimer, nullptr);
-			ptr_app->htimer = nullptr;
+			if (DeleteTimerQueueTimer (config.htimer, ptr_app->htimer, nullptr))
+				ptr_app->htimer = nullptr;
 		}
 
 		if (ptr_app->timer)
@@ -50,7 +50,7 @@ void _app_timer_create (HWND hwnd, const MFILTER_APPS* ptr_apps, time_t seconds)
 	_wfp_create3filters (ptr_apps, __LINE__);
 }
 
-size_t _app_timer_remove (HWND hwnd, const MFILTER_APPS* ptr_apps)
+size_t _app_timer_remove (HWND hwnd, const MFILTER_APPS *ptr_apps)
 {
 	if (!config.hengine || !ptr_apps || ptr_apps->empty ())
 		return false;
@@ -72,9 +72,11 @@ size_t _app_timer_remove (HWND hwnd, const MFILTER_APPS* ptr_apps)
 
 		if (ptr_app->htimer)
 		{
-			DeleteTimerQueueTimer (config.htimer, ptr_app->htimer, nullptr);
-			ptr_app->htimer = nullptr;
-			ptr_app->timer = 0;
+			if (DeleteTimerQueueTimer (config.htimer, ptr_app->htimer, nullptr))
+			{
+				ptr_app->htimer = nullptr;
+				ptr_app->timer = 0;
+			}
 
 			ptr_app->is_enabled = false;