diff --git a/drivers/atm/horizon.c b/drivers/atm/horizon.c
index c0ac728..6154123 100644
--- a/drivers/atm/horizon.c
+++ b/drivers/atm/horizon.c
@@ -635,7 +635,7 @@
 		// take care of rounding
 		switch (r) {
 			case round_down:
-				pre = (br+(c<<div)-1)/(c<<div);
+				pre = DIV_ROUND_UP(br, c<<div);
 				// but p must be non-zero
 				if (!pre)
 					pre = 1;
@@ -668,7 +668,7 @@
 			// take care of rounding
 			switch (r) {
 				case round_down:
-					pre = (br+(c<<div)-1)/(c<<div);
+					pre = DIV_ROUND_UP(br, c<<div);
 					break;
 				case round_nearest:
 					pre = (br+(c<<div)/2)/(c<<div);
@@ -698,7 +698,7 @@
 		if (bits)
 			*bits = (div<<CLOCK_SELECT_SHIFT) | (pre-1);
 		if (actual) {
-			*actual = (br + (pre<<div) - 1) / (pre<<div);
+			*actual = DIV_ROUND_UP(br, pre<<div);
 			PRINTD (DBG_QOS, "actual rate: %u", *actual);
 		}
 		return 0;
@@ -1967,7 +1967,7 @@
   // Set the max AAL5 cell count to be just enough to contain the
   // largest AAL5 frame that the user wants to receive
   wr_regw (dev, MAX_AAL5_CELL_COUNT_OFF,
-	   (max_rx_size + ATM_AAL5_TRAILER + ATM_CELL_PAYLOAD - 1) / ATM_CELL_PAYLOAD);
+	   DIV_ROUND_UP(max_rx_size + ATM_AAL5_TRAILER, ATM_CELL_PAYLOAD));
   
   // Enable receive
   wr_regw (dev, RX_CONFIG_OFF, rd_regw (dev, RX_CONFIG_OFF) | RX_ENABLE);