diff --git a/drivers/can/Kconfig.mcux b/drivers/can/Kconfig.mcux
index 7d27ddc5aed..474944019f0 100644
--- a/drivers/can/Kconfig.mcux
+++ b/drivers/can/Kconfig.mcux
@@ -15,7 +15,7 @@ config CAN_MAX_FILTER
 	depends on CAN_MCUX_FLEXCAN
 	default 5
 	range 1 15 if SOC_SERIES_KINETIS_KE1XF || SOC_SERIES_KINETIS_K6X
-	range 1 64 if SOC_SERIES_IMX_RT
+	range 1 63 if SOC_SERIES_IMX_RT
 	help
 	  Defines maximum number of concurrent active RX filters
 
diff --git a/drivers/can/can_mcux_flexcan.c b/drivers/can/can_mcux_flexcan.c
index 2df8116b17d..4c90bbad7b3 100644
--- a/drivers/can/can_mcux_flexcan.c
+++ b/drivers/can/can_mcux_flexcan.c
@@ -51,7 +51,7 @@ LOG_MODULE_REGISTER(can_mcux_flexcan, CONFIG_CAN_LOG_LEVEL);
  * RX message buffers (filters) will take up the first N message
  * buffers. The rest are available for TX use.
  */
-#define MCUX_FLEXCAN_MAX_RX CONFIG_CAN_MAX_FILTER
+#define MCUX_FLEXCAN_MAX_RX (CONFIG_CAN_MAX_FILTER + RX_START_IDX)
 #define MCUX_FLEXCAN_MAX_TX \
 	(FSL_FEATURE_FLEXCAN_HAS_MESSAGE_BUFFER_MAX_NUMBERn(0) \
 	- MCUX_FLEXCAN_MAX_RX)