diff --git a/reactos/drivers/dd/serial/circularbuffer.c b/reactos/drivers/dd/serial/circularbuffer.c
index 0b533b8db01..0c908f3bd07 100644
--- a/reactos/drivers/dd/serial/circularbuffer.c
+++ b/reactos/drivers/dd/serial/circularbuffer.c
@@ -47,9 +47,10 @@ PushCircularBufferEntry(
 	IN PCIRCULAR_BUFFER pBuffer,
 	IN UCHAR Entry)
 {
+	ULONG NextPosition;
 	DPRINT("Serial: PushCircularBufferEntry(pBuffer %p, Entry 0x%x)\n", pBuffer, Entry);
 	ASSERT(pBuffer->Length);
-	ULONG NextPosition = (pBuffer->WritePosition + 1) % pBuffer->Length;
+	NextPosition = (pBuffer->WritePosition + 1) % pBuffer->Length;
 	if (NextPosition == pBuffer->ReadPosition)
 		return STATUS_BUFFER_TOO_SMALL;
 	pBuffer->Buffer[pBuffer->WritePosition] = Entry;
diff --git a/reactos/drivers/dd/serial/serial.c b/reactos/drivers/dd/serial/serial.c
index 6fc66e56b2f..7d66d153ca9 100644
--- a/reactos/drivers/dd/serial/serial.c
+++ b/reactos/drivers/dd/serial/serial.c
@@ -26,6 +26,7 @@ DriverEntry(
 	IN PUNICODE_STRING RegPath)
 {
 	ULONG i;
+	static BOOLEAN FirstTime = TRUE;
 	
 	DriverObject->DriverUnload = DriverUnload;
 	DriverObject->DriverExtension->AddDevice = SerialAddDevice;
@@ -44,7 +45,6 @@ DriverEntry(
 	
 	/* FIXME: It seems that DriverEntry function may be called more
 	 * than once. Do only legacy detection the first time. */
-	static BOOLEAN FirstTime = TRUE;
 	if (FirstTime)
 	{
 		FirstTime = FALSE;