diff -pNaru5 a/ax99100_sp.c b/ax99100_sp.c
--- a/ax99100_sp.c	2023-08-07 06:18:10.000000000 -0400
+++ b/ax99100_sp.c	2023-12-18 02:09:56.226262255 -0500
@@ -2692,11 +2692,15 @@ static void serial99100_dma_tx_tasklet (
 }
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37)
 static DECLARE_MUTEX(serial99100_sem);
 #else
+#if LINUX_VERSION_CODE < KERNEL_VERSION(6,4,0)
 static DEFINE_SEMAPHORE(serial99100_sem);
+#else
+static DEFINE_SEMAPHORE(serial99100_sem,1);
+#endif
 #endif
 
 static struct uart_driver starex_serial_driver = {
         .owner                  = THIS_MODULE,
         .driver_name            = "AX99100",