diff --git a/ccid_common/ccid_slot_fsm.c b/ccid_common/ccid_slot_fsm.c
index 2338919..18aa61f 100644
--- a/ccid_common/ccid_slot_fsm.c
+++ b/ccid_common/ccid_slot_fsm.c
@@ -246,6 +246,7 @@
 		uint16_t F = iso7816_3_fi_table[cs->proposed_pars.fi];
 		uint8_t D = iso7816_3_di_table[cs->proposed_pars.di];
 		uint32_t fmax = iso7816_3_fmax_table[cs->proposed_pars.fi];
+		uint8_t D_or_one = D > 0 ? D : 1;
 
 		/* 7816-3 5.2.3
 		 * No  information  shall  be  exchanged  when  switching  the
@@ -256,7 +257,7 @@
 		 */
 		card_uart_ctrl(ss->cuart, CUART_CTL_SET_CLOCK_FREQ, fmax);
 		card_uart_ctrl(ss->cuart, CUART_CTL_SET_FD, F/D);
-		card_uart_ctrl(ss->cuart, CUART_CTL_WTIME, cs->proposed_pars.t0.waiting_integer * 960);
+		card_uart_ctrl(ss->cuart, CUART_CTL_WTIME, cs->proposed_pars.t0.waiting_integer * 960 * D_or_one);
 
 		cs->pars = cs->proposed_pars;
 		resp = ccid_gen_parameters_t0(cs, ss->seq, CCID_CMD_STATUS_OK, 0);