diff --git a/bacnet-stack/ports/bdk-atxx4-mstp/dlmstp.c b/bacnet-stack/ports/bdk-atxx4-mstp/dlmstp.c
index d66b1c69..35d83039 100644
--- a/bacnet-stack/ports/bdk-atxx4-mstp/dlmstp.c
+++ b/bacnet-stack/ports/bdk-atxx4-mstp/dlmstp.c
@@ -667,6 +667,7 @@ static void MSTP_Receive_Frame_FSM(
     return;
 }
 
+#ifdef MSTP_DEBUG_STATES
 static MSTP_MASTER_STATE Master_State_Log[128];
 static unsigned master_state_log_index = 0;
 void log_master_state(MSTP_MASTER_STATE state)
@@ -677,6 +678,9 @@ void log_master_state(MSTP_MASTER_STATE state)
         master_state_log_index = 0;
     }
 }
+#else
+    #define log_master_state(n) (void)n;
+#endif
 
 /* returns true if we need to transition immediately */
 static bool MSTP_Master_Node_FSM(
diff --git a/bacnet-stack/ports/bdk-atxx4-mstp/rs485.c b/bacnet-stack/ports/bdk-atxx4-mstp/rs485.c
index f3bc8c9a..5ba58cc6 100644
--- a/bacnet-stack/ports/bdk-atxx4-mstp/rs485.c
+++ b/bacnet-stack/ports/bdk-atxx4-mstp/rs485.c
@@ -46,8 +46,8 @@ static uint32_t Baud_Rate = 9600;
 /* turnaround_time_milliseconds = (Tturnaround*1000UL)/Baud_Rate; */
 
 /* buffer for storing received bytes - size must be power of two */
-uint8_t Receive_Buffer_Data[128];
-FIFO_BUFFER Receive_Buffer;
+static uint8_t Receive_Buffer_Data[128];
+static FIFO_BUFFER Receive_Buffer;
 
 static void rs485_rts_init(
     void)