diff --git a/sys/arm/at91/at91_pmc.c b/sys/arm/at91/at91_pmc.c
index a97849b2f31d..88810a6cdebd 100644
--- a/sys/arm/at91/at91_pmc.c
+++ b/sys/arm/at91/at91_pmc.c
@@ -506,7 +506,7 @@ at91_pmc_sense_main_clock(void)
 	 * AT91C_MAIN_CLOCK in the kernel config file.
 	 */
 	if (ckgr_val >= 21000000)
-		return ((ckgr_val + 250) / 500 * 500);
+		return (rounddown(ckgr_val + 250, 500));
 
 	/*
 	 * Try to find the standard frequency that match best.
diff --git a/sys/ddb/db_output.c b/sys/ddb/db_output.c
index a2afb6aba8e0..109c7a50e1d9 100644
--- a/sys/ddb/db_output.c
+++ b/sys/ddb/db_output.c
@@ -71,8 +71,7 @@ struct dbputchar_arg {
 static int	db_output_position = 0;		/* output column */
 static int	db_last_non_space = 0;		/* last non-space character */
 db_expr_t	db_tab_stop_width = 8;		/* how wide are tab stops? */
-#define	NEXT_TAB(i) \
-	((((i) + db_tab_stop_width) / db_tab_stop_width) * db_tab_stop_width)
+#define	NEXT_TAB(i) rounddown((i) + db_tab_stop_width, db_tab_stop_width)
 db_expr_t	db_max_width = 79;		/* output line width */
 db_expr_t	db_lines_per_page = 20;		/* lines per page */
 volatile int	db_pager_quit;			/* user requested quit */
diff --git a/sys/dev/acpi_support/acpi_hp.c b/sys/dev/acpi_support/acpi_hp.c
index 282803814dc5..ec8589659438 100644
--- a/sys/dev/acpi_support/acpi_hp.c
+++ b/sys/dev/acpi_support/acpi_hp.c
@@ -1033,7 +1033,8 @@ acpi_hp_hex_decode(char* buffer)
 	UINT8	*uin;
 	UINT8	uout;
 
-	if (((int)length/2)*2 == length || length < 10) return;
+	if (rounddown((int)length, 2) == length || length < 10)
+		return;
 
 	for (i = 0; i<length; ++i) {
 		if (!((i+1)%3)) {
diff --git a/sys/dev/cxgbe/t4_netmap.c b/sys/dev/cxgbe/t4_netmap.c
index 6f6df1095ef8..ba968d686c31 100644
--- a/sys/dev/cxgbe/t4_netmap.c
+++ b/sys/dev/cxgbe/t4_netmap.c
@@ -1119,7 +1119,7 @@ ncxgbe_attach(device_t dev)
 	 * freelist, and not the number of entries in the iq.  (These two are
 	 * not exactly the same due to the space taken up by the status page).
 	 */
-	na.num_rx_desc = (vi->qsize_rxq / 8) * 8;
+	na.num_rx_desc = rounddown(vi->qsize_rxq, 8);
 	na.nm_txsync = cxgbe_netmap_txsync;
 	na.nm_rxsync = cxgbe_netmap_rxsync;
 	na.nm_register = cxgbe_netmap_reg;
diff --git a/sys/dev/fb/fb.c b/sys/dev/fb/fb.c
index aa2d30005f41..183abdc3bfcb 100644
--- a/sys/dev/fb/fb.c
+++ b/sys/dev/fb/fb.c
@@ -86,7 +86,7 @@ vid_realloc_array(void)
 		return ENOMEM;
 
 	s = spltty();
-	newsize = ((adapters + ARRAY_DELTA)/ARRAY_DELTA)*ARRAY_DELTA;
+	newsize = rounddown(adapters + ARRAY_DELTA, ARRAY_DELTA);
 	new_adp = malloc(sizeof(*new_adp)*newsize, M_DEVBUF, M_WAITOK | M_ZERO);
 	new_vidsw = malloc(sizeof(*new_vidsw)*newsize, M_DEVBUF,
 	    M_WAITOK | M_ZERO);
diff --git a/sys/dev/fb/vesa.c b/sys/dev/fb/vesa.c
index cdd836cd3d3c..4ab83c30ff4b 100644
--- a/sys/dev/fb/vesa.c
+++ b/sys/dev/fb/vesa.c
@@ -1581,7 +1581,7 @@ vesa_set_origin(video_adapter_t *adp, off_t offset)
 	regs.R_DX = offset / adp->va_window_gran;
 	x86bios_intr(&regs, 0x10);
 
-	adp->va_window_orig = (offset/adp->va_window_gran)*adp->va_window_gran;
+	adp->va_window_orig = rounddown(offset, adp->va_window_gran);
 	return (0);			/* XXX */
 }
 
diff --git a/sys/dev/fb/vga.c b/sys/dev/fb/vga.c
index d0239b3a18b8..83b969470b5e 100644
--- a/sys/dev/fb/vga.c
+++ b/sys/dev/fb/vga.c
@@ -1252,7 +1252,7 @@ set_line_length(video_adapter_t *adp, int pixel)
 	break;
     case V_INFO_MM_PACKED:
 	count = (pixel + 7)/8;
-	bpl = ((pixel + 7)/8)*8;
+	bpl = rounddown(pixel + 7, 8);
 	break;
     case V_INFO_MM_TEXT:
 	count = (pixel + 7)/8;			/* columns */
diff --git a/sys/dev/iwn/if_iwn.c b/sys/dev/iwn/if_iwn.c
index bffa8de35fb9..01f28a00e98d 100644
--- a/sys/dev/iwn/if_iwn.c
+++ b/sys/dev/iwn/if_iwn.c
@@ -6335,7 +6335,7 @@ iwn_set_pslevel(struct iwn_softc *sc, int dtim, int level, int async)
 		if (max == (uint32_t)-1)
 			max = dtim * (skip_dtim + 1);
 		else if (max > dtim)
-			max = (max / dtim) * dtim;
+			max = rounddown(max, dtim);
 	} else
 		max = dtim;
 	for (i = 0; i < 5; i++)
diff --git a/sys/dev/kbd/kbd.c b/sys/dev/kbd/kbd.c
index 45f483ac1a23..985a96040405 100644
--- a/sys/dev/kbd/kbd.c
+++ b/sys/dev/kbd/kbd.c
@@ -96,7 +96,7 @@ kbd_realloc_array(void)
 	int s;
 
 	s = spltty();
-	newsize = ((keyboards + ARRAY_DELTA)/ARRAY_DELTA)*ARRAY_DELTA;
+	newsize = rounddown(keyboards + ARRAY_DELTA, ARRAY_DELTA);
 	new_kbd = malloc(sizeof(*new_kbd)*newsize, M_DEVBUF, M_NOWAIT|M_ZERO);
 	if (new_kbd == NULL) {
 		splx(s);
diff --git a/sys/dev/syscons/scmouse.c b/sys/dev/syscons/scmouse.c
index 589506643622..db26787c264e 100644
--- a/sys/dev/syscons/scmouse.c
+++ b/sys/dev/syscons/scmouse.c
@@ -495,7 +495,7 @@ mouse_cut_start(scr_stat *scp)
 	    i = skip_spc_left(scp, scp->mouse_pos) + 1;
 	    s = spltty();
 	    scp->mouse_cut_start =
-	        (scp->mouse_pos / scp->xsize) * scp->xsize + i;
+	        rounddown(scp->mouse_pos, scp->xsize) + i;
 	    scp->mouse_cut_end =
 	        (scp->mouse_pos / scp->xsize + 1) * scp->xsize - 1;
 	    splx(s);
@@ -540,7 +540,7 @@ mouse_cut_word(scr_stat *scp)
      * unless user specified SC_CUT_SEPCHARS in his kernel config file.
      */
     if (scp->status & MOUSE_VISIBLE) {
-	sol = (scp->mouse_pos / scp->xsize) * scp->xsize;
+	sol = rounddown(scp->mouse_pos, scp->xsize);
 	eol = sol + scp->xsize;
 	c = sc_vtb_getc(&scp->vtb, scp->mouse_pos);
 	if (IS_SEP_CHAR(c)) {
@@ -589,7 +589,7 @@ mouse_cut_line(scr_stat *scp)
     int from;
 
     if (scp->status & MOUSE_VISIBLE) {
-	from = (scp->mouse_pos / scp->xsize) * scp->xsize;
+	from = rounddown(scp->mouse_pos, scp->xsize);
 	mouse_do_cut(scp, from, from + scp->xsize - 1);
 	len = strlen(cut_buffer);
 	if (cut_buffer[len - 1] == '\r')
diff --git a/sys/dev/syscons/scvgarndr.c b/sys/dev/syscons/scvgarndr.c
index fc7f02f58fef..2d2651746004 100644
--- a/sys/dev/syscons/scvgarndr.c
+++ b/sys/dev/syscons/scvgarndr.c
@@ -1035,7 +1035,7 @@ draw_pxlmouse_planar(scr_stat *scp, int x, int y)
 
 	line_width = scp->sc->adp->va_line_width;
 	xoff = (x - scp->xoff*8)%8;
-	yoff = y - (y/line_width)*line_width;
+	yoff = y - rounddown(y, line_width);
 	ymax = imin(y + 16, scp->ypixel);
 
 	outw(GDCIDX, 0x0805);		/* read mode 1, write mode 0 */
diff --git a/sys/dev/vt/hw/vga/vt_vga.c b/sys/dev/vt/hw/vga/vt_vga.c
index e81dcba7663a..9788b7e67265 100644
--- a/sys/dev/vt/hw/vga/vt_vga.c
+++ b/sys/dev/vt/hw/vga/vt_vga.c
@@ -912,7 +912,7 @@ vga_bitblt_bitmap(struct vt_device *vd, const struct vt_window *vw,
 	uint8_t pattern_2colors;
 
 	/* Align coordinates with the 8-pxels grid. */
-	x1 = x / VT_VGA_PIXELS_BLOCK * VT_VGA_PIXELS_BLOCK;
+	x1 = rounddown(x, VT_VGA_PIXELS_BLOCK);
 	y1 = y;
 
 	x2 = roundup(x + width, VT_VGA_PIXELS_BLOCK);
diff --git a/sys/dev/vt/vt_core.c b/sys/dev/vt/vt_core.c
index 2884c57d0358..a90ab9f45adc 100644
--- a/sys/dev/vt/vt_core.c
+++ b/sys/dev/vt/vt_core.c
@@ -640,9 +640,9 @@ vt_compute_drawable_area(struct vt_window *vw)
 	if (vt_draw_logo_cpus)
 		vw->vw_draw_area.tr_begin.tp_row += vt_logo_sprite_height;
 	vw->vw_draw_area.tr_end.tp_col = vw->vw_draw_area.tr_begin.tp_col +
-	    vd->vd_width / vf->vf_width * vf->vf_width;
+	    rounddown(vd->vd_width, vf->vf_width);
 	vw->vw_draw_area.tr_end.tp_row = vw->vw_draw_area.tr_begin.tp_row +
-	    height / vf->vf_height * vf->vf_height;
+	    rounddown(height, vf->vf_height);
 }
 
 static void
diff --git a/sys/dev/wpi/if_wpi.c b/sys/dev/wpi/if_wpi.c
index 897b986eec36..acaa8212c804 100644
--- a/sys/dev/wpi/if_wpi.c
+++ b/sys/dev/wpi/if_wpi.c
@@ -3814,7 +3814,7 @@ wpi_set_pslevel(struct wpi_softc *sc, uint8_t dtim, int level, int async)
 		if (max == (uint32_t)-1)
 			max = dtim * (skip_dtim + 1);
 		else if (max > dtim)
-			max = (max / dtim) * dtim;
+			max = rounddown(max, dtim);
 	} else
 		max = dtim;
 
diff --git a/sys/fs/nandfs/nandfs_vfsops.c b/sys/fs/nandfs/nandfs_vfsops.c
index 7132635efdca..97d2273d4ba8 100644
--- a/sys/fs/nandfs/nandfs_vfsops.c
+++ b/sys/fs/nandfs/nandfs_vfsops.c
@@ -331,8 +331,8 @@ nandfs_write_superblock_at(struct nandfs_device *fsdev,
 	    super->s_last_pseg, super->s_last_cno, super->s_last_seq,
 	    super->s_wtime, index));
 
-	read_block = btodb(offset + ((index / sb_per_sector) * sb_per_sector)
-	    * sizeof(struct nandfs_super_block));
+	read_block = btodb(offset + rounddown(index, sb_per_sector) *
+	    sizeof(struct nandfs_super_block));
 
 	DPRINTF(SYNC, ("%s: read_block %#x\n", __func__, read_block));
 
diff --git a/sys/geom/virstor/g_virstor.c b/sys/geom/virstor/g_virstor.c
index 7393c10c984a..72d042d60592 100644
--- a/sys/geom/virstor/g_virstor.c
+++ b/sys/geom/virstor/g_virstor.c
@@ -1257,7 +1257,7 @@ virstor_check_and_run(struct g_virstor_softc *sc)
 		bs = MIN(MAXPHYS, sc->map_size - count);
 		if (bs % sc->sectorsize != 0) {
 			/* Check for alignment errors */
-			bs = (bs / sc->sectorsize) * sc->sectorsize;
+			bs = rounddown(bs, sc->sectorsize);
 			if (bs == 0)
 				break;
 			LOG_MSG(LVL_ERROR, "Trouble: map is not sector-aligned "
@@ -1723,13 +1723,12 @@ g_virstor_start(struct bio *b)
 				 * sc_offset will end up pointing to the drive
 				 * sector. */
 				s_offset = chunk_index * sizeof *me;
-				s_offset = (s_offset / sc->sectorsize) *
-				    sc->sectorsize;
+				s_offset = rounddown(s_offset, sc->sectorsize);
 
 				/* data_me points to map entry sector
-				 * in memory (analoguos to offset) */
-				data_me = &sc->map[(chunk_index /
-				    sc->me_per_sector) * sc->me_per_sector];
+				 * in memory (analogous to offset) */
+				data_me = &sc->map[rounddown(chunk_index,
+				    sc->me_per_sector)];
 
 				/* Commit sector with map entry to storage */
 				cb->bio_to = sc->components[0].gcons->provider;
diff --git a/sys/libkern/crc32.c b/sys/libkern/crc32.c
index c0b464cee388..65331ce2fde3 100644
--- a/sys/libkern/crc32.c
+++ b/sys/libkern/crc32.c
@@ -684,7 +684,7 @@ crc32c_sb8_64_bit(uint32_t crc,
 	uint32_t running_length;
 	uint32_t end_bytes;
 
-	running_length = ((length - init_bytes) / 8) * 8;
+	running_length = rounddown(length - init_bytes, 8);
 	end_bytes = length - init_bytes - running_length;
 
 	for (li = 0; li < init_bytes; li++)
diff --git a/sys/mips/atheros/ar934x_chip.c b/sys/mips/atheros/ar934x_chip.c
index b5b804f000d7..f59d4aaa5285 100644
--- a/sys/mips/atheros/ar934x_chip.c
+++ b/sys/mips/atheros/ar934x_chip.c
@@ -437,7 +437,7 @@ ar934x_chip_gpio_output_configure(int gpio, uint8_t func)
 	if (gpio > AR934X_GPIO_COUNT)
 		return;
 
-	reg = AR934X_GPIO_REG_OUT_FUNC0 + 4 * (gpio / 4);
+	reg = AR934X_GPIO_REG_OUT_FUNC0 + rounddown(gpio, 4);
 	s = 8 * (gpio % 4);
 
 	/* read-modify-write */
diff --git a/sys/mips/atheros/qca953x_chip.c b/sys/mips/atheros/qca953x_chip.c
index a262a9f8b078..88127b4ac691 100644
--- a/sys/mips/atheros/qca953x_chip.c
+++ b/sys/mips/atheros/qca953x_chip.c
@@ -360,7 +360,7 @@ qca953x_chip_gpio_output_configure(int gpio, uint8_t func)
 	if (gpio > QCA953X_GPIO_COUNT)
 		return;
 
-	reg = QCA953X_GPIO_REG_OUT_FUNC0 + 4 * (gpio / 4);
+	reg = QCA953X_GPIO_REG_OUT_FUNC0 + rounddown(gpio, 4);
 	s = 8 * (gpio % 4);
 
 	/* read-modify-write */
diff --git a/sys/mips/atheros/qca955x_chip.c b/sys/mips/atheros/qca955x_chip.c
index b4d54fa87334..d963cc6f2b68 100644
--- a/sys/mips/atheros/qca955x_chip.c
+++ b/sys/mips/atheros/qca955x_chip.c
@@ -369,7 +369,7 @@ qca955x_chip_gpio_output_configure(int gpio, uint8_t func)
 	if (gpio > QCA955X_GPIO_COUNT)
 		return;
 
-	reg = QCA955X_GPIO_REG_OUT_FUNC0 + 4 * (gpio / 4);
+	reg = QCA955X_GPIO_REG_OUT_FUNC0 + rounddown(gpio, 4);
 	s = 8 * (gpio % 4);
 
 	/* read-modify-write */
diff --git a/sys/rpc/clnt_dg.c b/sys/rpc/clnt_dg.c
index 36e63c674673..d9d5e41422ab 100644
--- a/sys/rpc/clnt_dg.c
+++ b/sys/rpc/clnt_dg.c
@@ -219,8 +219,8 @@ clnt_dg_create(
 	/*
 	 * Should be multiple of 4 for XDR.
 	 */
-	sendsz = ((sendsz + 3) / 4) * 4;
-	recvsz = ((recvsz + 3) / 4) * 4;
+	sendsz = rounddown(sendsz + 3, 4);
+	recvsz = rounddown(recvsz + 3, 4);
 	cu = mem_alloc(sizeof (*cu));
 	cu->cu_threads = 0;
 	cu->cu_closing = FALSE;