diff --git a/sys/dev/uart/uart_cpu_fdt.c b/sys/dev/uart/uart_cpu_fdt.c
index 9bf35496e68e..356049b9ae3e 100644
--- a/sys/dev/uart/uart_cpu_fdt.c
+++ b/sys/dev/uart/uart_cpu_fdt.c
@@ -62,9 +62,10 @@ uart_fdt_get_clock(phandle_t node, pcell_t *cell)
 {
 	pcell_t clock;
 
+	/* clock-frequency is a FreeBSD-only extention. */
 	if ((OF_getprop(node, "clock-frequency", &clock,
 	    sizeof(clock))) <= 0)
-		return (ENXIO);
+		clock = 0;
 
 	if (clock == 0)
 		/* Try to retrieve parent 'bus-frequency' */