diff --git a/src/sys/driver.h b/src/sys/driver.h
index 45a2a434..89ab6e3b 100644
--- a/src/sys/driver.h
+++ b/src/sys/driver.h
@@ -347,6 +347,8 @@ VOID FspQueueDelayedWorkItem(FSP_DELAYED_WORK_ITEM *DelayedWorkItem, LARGE_INTEG
 
 /* I/O queue */
 #define FspIoqTimeout                   ((PIRP)1)
+#define FspIoqPostIrp(Q, I, R)          FspIoqPostIrpEx(Q, I, TRUE, R)
+#define FspIoqPostIrpNoCap(Q, I, R)     FspIoqPostIrpEx(Q, I, FALSE, R)
 typedef struct
 {
     KSPIN_LOCK SpinLock;
@@ -367,7 +369,7 @@ VOID FspIoqDelete(FSP_IOQ *Ioq);
 VOID FspIoqStop(FSP_IOQ *Ioq);
 BOOLEAN FspIoqStopped(FSP_IOQ *Ioq);
 VOID FspIoqRemoveExpired(FSP_IOQ *Ioq);
-BOOLEAN FspIoqPostIrp(FSP_IOQ *Ioq, PIRP Irp, NTSTATUS *PResult);
+BOOLEAN FspIoqPostIrpEx(FSP_IOQ *Ioq, PIRP Irp, BOOLEAN CheckCapacity, NTSTATUS *PResult);
 PIRP FspIoqNextPendingIrp(FSP_IOQ *Ioq, PLARGE_INTEGER Timeout);
 BOOLEAN FspIoqStartProcessingIrp(FSP_IOQ *Ioq, PIRP Irp);
 PIRP FspIoqEndProcessingIrp(FSP_IOQ *Ioq, UINT_PTR IrpHint);
diff --git a/src/sys/ioq.c b/src/sys/ioq.c
index 83015ba5..6cc91148 100644
--- a/src/sys/ioq.c
+++ b/src/sys/ioq.c
@@ -299,11 +299,11 @@ VOID FspIoqRemoveExpired(FSP_IOQ *Ioq)
         Ioq->CompleteCanceledIrp(Irp);
 }
 
-BOOLEAN FspIoqPostIrp(FSP_IOQ *Ioq, PIRP Irp, NTSTATUS *PResult)
+BOOLEAN FspIoqPostIrpEx(FSP_IOQ *Ioq, PIRP Irp, BOOLEAN CheckCapacity, NTSTATUS *PResult)
 {
     NTSTATUS Result;
     FspIrpTimestamp(Irp) = QueryInterruptTimeInSec() + Ioq->IrpTimeout;
-    Result = IoCsqInsertIrpEx(&Ioq->PendingIoCsq, Irp, 0, (PVOID)1);
+    Result = IoCsqInsertIrpEx(&Ioq->PendingIoCsq, Irp, 0, (PVOID)CheckCapacity);
     if (NT_SUCCESS(Result))
         return TRUE;
     if (0 != PResult)