diff --git a/drivers/video/fbdev/riva/riva_hw.c b/drivers/video/fbdev/riva/riva_hw.c
index 8b829b720064..f292079566cf 100644
--- a/drivers/video/fbdev/riva/riva_hw.c
+++ b/drivers/video/fbdev/riva/riva_hw.c
@@ -436,6 +436,9 @@ static char nv3_arb(nv3_fifo_info * res_info, nv3_sim_state * state,  nv3_arb_in
     vmisses = 2;
     eburst_size = state->memory_width * 1;
     mburst_size = 32;
+    if (!state->mclk_khz)
+	return (0);
+
     gns = 1000000 * (gmisses*state->mem_page_miss + state->mem_latency)/state->mclk_khz;
     ainfo->by_gfacc = gns*ainfo->gdrain_rate/1000000;
     ainfo->wcmocc = 0;