diff --git a/can-calc-bit-timing.c b/can-calc-bit-timing.c
index 4a79c3c..6d5b6d0 100644
--- a/can-calc-bit-timing.c
+++ b/can-calc-bit-timing.c
@@ -363,6 +363,7 @@ static struct calc_bittiming_const can_calc_consts[] = {
 		},
 		.ref_clk = {
 			/* The mcp251x uses half of the external OSC clock as the base clock */
+			{ .clk =  8000000 / 2, },
 			{ .clk = 16000000 / 2, },
 			{ .clk = 20000000 / 2, },
 		},