diff --git a/src/gos/chibios.c b/src/gos/chibios.c
index cf02b3e2..7d64fe1c 100644
--- a/src/gos/chibios.c
+++ b/src/gos/chibios.c
@@ -89,6 +89,13 @@ bool_t gfxSemWait(gfxSem *psem, delaytime_t ms) {
 	return chSemWaitTimeout(&psem->sem, MS2ST(ms)) != RDY_TIMEOUT;
 }
 
+bool_t gfxSemWaitI(gfxSem *psem) {
+	if (chSemGetCounterI(&psem->sem) <= 0)
+		return FALSE;
+	chSemFastWaitI(&psem->sem);
+	return TRUE;
+}
+
 void gfxSemSignal(gfxSem *psem) {
 	chSysLock();
 
diff --git a/src/gos/chibios.h b/src/gos/chibios.h
index 6373aa43..1db9482e 100644
--- a/src/gos/chibios.h
+++ b/src/gos/chibios.h
@@ -82,6 +82,7 @@ void gfxSleepMicroseconds(delaytime_t ms);
 void gfxSemInit(gfxSem *psem, semcount_t val, semcount_t limit);
 void gfxSemDestroy(gfxSem *psem);
 bool_t gfxSemWait(gfxSem *psem, delaytime_t ms);
+bool_t gfxSemWaitI(gfxSem *psem);
 void gfxSemSignal(gfxSem *psem);
 void gfxSemSignalI(gfxSem *psem);
 #define gfxSemCounterI(psem)		((psem)->sem.s_cnt)
diff --git a/src/gos/linux.h b/src/gos/linux.h
index f8b049e9..f92fc4e9 100644
--- a/src/gos/linux.h
+++ b/src/gos/linux.h
@@ -46,6 +46,7 @@ typedef pthread_mutex_t		gfxMutex;
 #define gfxMutexDestroy(pmtx)			pthread_mutex_destroy(pmtx)
 #define gfxMutexEnter(pmtx)				pthread_mutex_lock(pmtx)
 #define gfxMutexExit(pmtx)				pthread_mutex_unlock(pmtx)
+#define gfxSemWaitI(psem)				gfxSemWait(psem, TIME_IMMEDIATE)
 #define gfxSemSignalI(psem)				gfxSemSignal(psem)
 #define gfxSemCounterI(pSem)			((pSem)->cnt)
 
diff --git a/src/gos/osx.h b/src/gos/osx.h
index 56e0551e..80b07eec 100644
--- a/src/gos/osx.h
+++ b/src/gos/osx.h
@@ -45,6 +45,7 @@ typedef pthread_mutex_t		gfxMutex;
 #define gfxMutexDestroy(pmtx)			pthread_mutex_destroy(pmtx)
 #define gfxMutexEnter(pmtx)				pthread_mutex_lock(pmtx)
 #define gfxMutexExit(pmtx)				pthread_mutex_unlock(pmtx)
+#define gfxSemWaitI(psem)				gfxSemWait(psem, TIME_IMMEDIATE)
 #define gfxSemSignalI(psem)				gfxSemSignal(psem)
 #define gfxSemCounterI(pSem)			((pSem)->cnt)
 
diff --git a/src/gos/raw32.c b/src/gos/raw32.c
index 61d09761..2fdfdf68 100644
--- a/src/gos/raw32.c
+++ b/src/gos/raw32.c
@@ -346,6 +346,13 @@ bool_t gfxSemWait(gfxSem *psem, delaytime_t ms) {
 	return TRUE;
 }
 
+bool_t gfxSemWaitI(gfxSem *psem) {
+	if (psem->cnt <= 0)
+		return FALSE;
+	psem->cnt--;
+	return TRUE;
+}
+
 void gfxSemSignal(gfxSem *psem) {
 	INTERRUPTS_OFF();
 	gfxSemSignalI(psem);
diff --git a/src/gos/raw32.h b/src/gos/raw32.h
index eb5b5e18..d4e8e548 100644
--- a/src/gos/raw32.h
+++ b/src/gos/raw32.h
@@ -110,6 +110,7 @@ extern "C" {
 	void gfxMutexExit(gfxMutex *pmutex);
 	void gfxSemInit(gfxSem *psem, semcount_t val, semcount_t limit);
 	bool_t gfxSemWait(gfxSem *psem, delaytime_t ms);
+	bool_t gfxSemWaitI(gfxSem *psem);
 	void gfxSemSignal(gfxSem *psem);
 	void gfxSemSignalI(gfxSem *psem);
 	gfxThreadHandle gfxThreadCreate(void *stackarea, size_t stacksz, threadpriority_t prio, DECLARE_THREAD_FUNCTION((*fn),p), void *param);
diff --git a/src/gos/sys_defs.h b/src/gos/sys_defs.h
index b913fb66..f10ddd62 100644
--- a/src/gos/sys_defs.h
+++ b/src/gos/sys_defs.h
@@ -327,6 +327,19 @@
 	 */
 	bool_t gfxSemWait(gfxSem *psem, delaytime_t ms);
 
+	/**
+	 * @brief	Test if a wait on a semaphore can be satisfied immediately
+	 * @details	Equivalent to @p gfxSemWait(psem, TIME_IMMEDIATE) except it can be called at interrupt level
+	 * @return	FALSE if the wait would occur occurred otherwise TRUE
+	 *
+	 * @param[in] psem		A pointer to the semaphore
+	 * @param[in] ms		The maximum time to wait for the semaphore
+	 *
+	 * @iclass
+	 * @api
+	 */
+	bool_t gfxSemWaitI(gfxSem *psem);
+
 	/**
 	 * @brief	Signal a semaphore
 	 * @details	The semaphore counter is increased and if the result is non-positive then a waiting thread
diff --git a/src/gos/win32.h b/src/gos/win32.h
index c704a288..8a5d9025 100644
--- a/src/gos/win32.h
+++ b/src/gos/win32.h
@@ -74,6 +74,7 @@ typedef HANDLE gfxThreadHandle;
 #define gfxMutexExit(pmutex)			ReleaseMutex(*(pmutex))
 #define gfxSemInit(psem, val, limit)	*(psem) = CreateSemaphore(0, val, limit, 0)
 #define gfxSemDestroy(psem)				CloseHandle(*(psem))
+#define gfxSemWaitI(psem)				gfxSemWait((psem), TIME_IMMEDIATE)
 #define gfxSemSignal(psem)				ReleaseSemaphore(*(psem), 1, 0)
 #define gfxSemSignalI(psem)				ReleaseSemaphore(*(psem), 1, 0)
 #define gfxSemCounterI(psem)			gfxSemCounter(psem)