diff --git a/gim/box.go b/gim/box.go
index af9d181..5dfaf89 100644
--- a/gim/box.go
+++ b/gim/box.go
@@ -63,8 +63,8 @@ func (b box) draw(buf *terminal.Buffer) {
 	buf.DrawRect(rect, terminal.SingleLine)
 
 	if b.bodyBuf != nil {
-		center := rect.Center(rounder)
+		center := rect.Center()
 		bodyBufRect := geo.Rect{Size: b.bodyBuf.Size()}
-		buf.DrawBuffer(bodyBufRect.Centered(center, rounder).TopLeft, b.bodyBuf)
+		buf.DrawBuffer(bodyBufRect.Centered(center).TopLeft, b.bodyBuf)
 	}
 }
diff --git a/gim/geo/geo.go b/gim/geo/geo.go
index a93256b..44900d4 100644
--- a/gim/geo/geo.go
+++ b/gim/geo/geo.go
@@ -59,9 +59,8 @@ func (xy XY) Unit() XY {
 	return xy
 }
 
-// Len returns the length (aka magnitude) of the XY as a vector, using the
-// Rounder to round to an int
-func (xy XY) Len(r Rounder) int {
+// Len returns the length (aka magnitude) of the XY as a vector.
+func (xy XY) Len() int {
 	if xy[0] == 0 {
 		return abs(xy[1])
 	} else if xy[1] == 0 {
@@ -70,7 +69,7 @@ func (xy XY) Len(r Rounder) int {
 
 	xyf := xy.toF64()
 	lf := math.Sqrt((xyf[0] * xyf[0]) + (xyf[1] * xyf[1]))
-	return r.Round(lf)
+	return Rounder.Round(lf)
 }
 
 // Add returns the result of adding the two XYs' fields individually
@@ -87,13 +86,12 @@ func (xy XY) Mul(xy2 XY) XY {
 	return xy
 }
 
-// Div returns the results of dividing the two XYs' field individually, using
-// the Rounder to resolve floating results
-func (xy XY) Div(xy2 XY, r Rounder) XY {
+// Div returns the results of dividing the two XYs' field individually.
+func (xy XY) Div(xy2 XY) XY {
 	xyf, xy2f := xy.toF64(), xy2.toF64()
 	return XY{
-		r.Round(xyf[0] / xy2f[0]),
-		r.Round(xyf[1] / xy2f[1]),
+		Rounder.Round(xyf[0] / xy2f[0]),
+		Rounder.Round(xyf[1] / xy2f[1]),
 	}
 }
 
@@ -113,10 +111,9 @@ func (xy XY) Sub(xy2 XY) XY {
 	return xy.Add(xy2.Inv())
 }
 
-// Midpoint returns the midpoint between the two XYs. The rounder indicates what
-// to do about non-whole values when they're come across
-func (xy XY) Midpoint(xy2 XY, r Rounder) XY {
-	return xy.Add(xy2.Sub(xy).Div(XY{2, 2}, r))
+// Midpoint returns the midpoint between the two XYs.
+func (xy XY) Midpoint(xy2 XY) XY {
+	return xy.Add(xy2.Sub(xy).Div(XY{2, 2}))
 }
 
 // Min returns an XY whose fields are the minimum values of the two XYs'
diff --git a/gim/geo/rect.go b/gim/geo/rect.go
index a38f72b..a0d3391 100644
--- a/gim/geo/rect.go
+++ b/gim/geo/rect.go
@@ -82,32 +82,30 @@ func (r Rect) Edge(dir, secDir XY) Edge {
 }
 
 // Midpoint returns the point which is the midpoint of the Edge
-func (e Edge) Midpoint(rounder Rounder) XY {
-	return e[0].Midpoint(e[1], rounder)
+func (e Edge) Midpoint() XY {
+	return e[0].Midpoint(e[1])
 }
 
-func (r Rect) halfSize(rounder Rounder) XY {
-	return r.Size.Div(XY{2, 2}, rounder)
+func (r Rect) halfSize() XY {
+	return r.Size.Div(XY{2, 2})
 }
 
-// Center returns the centerpoint of the rectangle, using the given Rounder to
-// resolve non-integers
-func (r Rect) Center(rounder Rounder) XY {
-	return r.TopLeft.Add(r.halfSize(rounder))
+// Center returns the centerpoint of the rectangle.
+func (r Rect) Center() XY {
+	return r.TopLeft.Add(r.halfSize())
 }
 
 // Translate returns an instance of Rect which is the same as this one but
-// translated by the given amount
+// translated by the given amount.
 func (r Rect) Translate(by XY) Rect {
 	r.TopLeft = r.TopLeft.Add(by)
 	return r
 }
 
 // Centered returns an instance of Rect which is this one but translated to be
-// centered on the given point. It will use the given Rounder to resolve
-// non-integers
-func (r Rect) Centered(on XY, rounder Rounder) Rect {
-	r.TopLeft = on.Sub(r.halfSize(rounder))
+// centered on the given point.
+func (r Rect) Centered(on XY) Rect {
+	r.TopLeft = on.Sub(r.halfSize())
 	return r
 }
 
diff --git a/gim/geo/rect_test.go b/gim/geo/rect_test.go
index d7301bf..80b2274 100644
--- a/gim/geo/rect_test.go
+++ b/gim/geo/rect_test.go
@@ -38,30 +38,20 @@ func TestRect(t *T) {
 }
 
 func TestRectCenter(t *T) {
-	assertCentered := func(exp, given Rect, center XY, rounder Rounder) {
-		got := given.Centered(center, rounder)
+	assertCentered := func(exp, given Rect, center XY) {
+		got := given.Centered(center)
 		assert.Equal(t, exp, got)
-		assert.Equal(t, center, got.Center(rounder))
+		assert.Equal(t, center, got.Center())
 	}
 
 	{
 		r := Rect{
 			Size: XY{4, 4},
 		}
-		assert.Equal(t, XY{2, 2}, r.Center(Round))
-		assert.Equal(t, XY{2, 2}, r.Center(Floor))
-		assert.Equal(t, XY{2, 2}, r.Center(Ceil))
+		assert.Equal(t, XY{2, 2}, r.Center())
 		assertCentered(
 			Rect{TopLeft: XY{1, 1}, Size: XY{4, 4}},
-			r, XY{3, 3}, Round,
-		)
-		assertCentered(
-			Rect{TopLeft: XY{1, 1}, Size: XY{4, 4}},
-			r, XY{3, 3}, Floor,
-		)
-		assertCentered(
-			Rect{TopLeft: XY{1, 1}, Size: XY{4, 4}},
-			r, XY{3, 3}, Ceil,
+			r, XY{3, 3},
 		)
 	}
 
@@ -69,20 +59,10 @@ func TestRectCenter(t *T) {
 		r := Rect{
 			Size: XY{5, 5},
 		}
-		assert.Equal(t, XY{3, 3}, r.Center(Round))
-		assert.Equal(t, XY{2, 2}, r.Center(Floor))
-		assert.Equal(t, XY{3, 3}, r.Center(Ceil))
+		assert.Equal(t, XY{3, 3}, r.Center())
 		assertCentered(
 			Rect{TopLeft: XY{0, 0}, Size: XY{5, 5}},
-			r, XY{3, 3}, Round,
-		)
-		assertCentered(
-			Rect{TopLeft: XY{1, 1}, Size: XY{5, 5}},
-			r, XY{3, 3}, Floor,
-		)
-		assertCentered(
-			Rect{TopLeft: XY{0, 0}, Size: XY{5, 5}},
-			r, XY{3, 3}, Ceil,
+			r, XY{3, 3},
 		)
 	}
 }
diff --git a/gim/geo/round.go b/gim/geo/round.go
index 822a4e2..b869831 100644
--- a/gim/geo/round.go
+++ b/gim/geo/round.go
@@ -1,44 +1,33 @@
 package geo
 
 import (
-	"fmt"
 	"math"
 )
 
-// Rounder describes how a floating point number should be converted to an int
-type Rounder int
+// RounderFunc is a function which converts a floating point number into an
+// integer.
+type RounderFunc func(float64) int64
 
-const (
-	// Round will round up or down depending on the number itself
-	Round Rounder = iota
+// Round is helper for calling the RounderFunc and converting the result to an
+// int.
+func (rf RounderFunc) Round(f float64) int {
+	return int(rf(f))
+}
 
-	// Floor will use the math.Floor function
-	Floor
-
-	// Ceil will use the math.Ceil function
-	Ceil
-)
-
-// Round64 converts a float to an in64 based on the rounding function indicated
-// by the Rounder's value
-func (r Rounder) Round64(f float64) int64 {
-	switch r {
-	case Round:
+// A few RounderFuncs which can be used. Set the Rounder global variable to pick
+// one.
+var (
+	Floor RounderFunc = func(f float64) int64 { return int64(math.Floor(f)) }
+	Ceil  RounderFunc = func(f float64) int64 { return int64(math.Ceil(f)) }
+	Round RounderFunc = func(f float64) int64 {
 		if f < 0 {
 			f = math.Ceil(f - 0.5)
 		}
 		f = math.Floor(f + 0.5)
-	case Floor:
-		f = math.Floor(f)
-	case Ceil:
-		f = math.Ceil(f)
-	default:
-		panic(fmt.Sprintf("invalid Rounder: %#v", r))
+		return int64(f)
 	}
-	return int64(f)
-}
+)
 
-// Round is like Round64 but convers the int64 to an int
-func (r Rounder) Round(f float64) int {
-	return int(r.Round64(f))
-}
+// Rounder is the RounderFunc which will be used by all functions and methods in
+// this package when needed.
+var Rounder = Ceil
diff --git a/gim/line.go b/gim/line.go
index ebcf8e1..cb6c9ec 100644
--- a/gim/line.go
+++ b/gim/line.go
@@ -26,8 +26,8 @@ func (l line) draw(buf *terminal.Buffer, flowDir, secFlowDir geo.XY) {
 
 	// draw the body
 	if l.bodyBuf != nil {
-		mid := start.Midpoint(end, rounder)
+		mid := start.Midpoint(end)
 		bodyBufRect := geo.Rect{Size: l.bodyBuf.Size()}
-		buf.DrawBuffer(bodyBufRect.Centered(mid, rounder).TopLeft, l.bodyBuf)
+		buf.DrawBuffer(bodyBufRect.Centered(mid).TopLeft, l.bodyBuf)
 	}
 }
diff --git a/gim/main.go b/gim/main.go
index c2ac47d..2c37487 100644
--- a/gim/main.go
+++ b/gim/main.go
@@ -23,7 +23,6 @@ import (
 const (
 	framerate   = 10
 	frameperiod = time.Second / time.Duration(framerate)
-	rounder     = geo.Ceil
 )
 
 func debugf(str string, args ...interface{}) {
@@ -81,7 +80,7 @@ func main() {
 	rand.Seed(time.Now().UnixNano())
 	term := terminal.New()
 	wSize := term.WindowSize()
-	center := geo.Zero.Midpoint(wSize, rounder)
+	center := geo.Zero.Midpoint(wSize)
 
 	g, start := mkGraph()
 	v := view{
@@ -93,7 +92,7 @@ func main() {
 
 	buf := terminal.NewBuffer()
 	v.draw(buf)
-	bufRect := geo.Rect{Size: buf.Size()}.Centered(center, rounder)
+	bufRect := geo.Rect{Size: buf.Size()}.Centered(center)
 
 	term.Clear()
 	term.WriteBuffer(bufRect.TopLeft, buf)
diff --git a/gim/terminal/shape.go b/gim/terminal/shape.go
index a2fcd85..3bbfb88 100644
--- a/gim/terminal/shape.go
+++ b/gim/terminal/shape.go
@@ -144,10 +144,7 @@ func (b *Buffer) DrawLine(start, end, dir geo.XY, ls LineStyle) {
 	var perpDir geo.XY
 	perpDir[0], perpDir[1] = dir[1], dir[0]
 	dirSec := end.Sub(start).Mul(perpDir.Abs()).Unit()
-
-	// TODO gross that this doesn't have some way of discovering the rounder.
-	// Maybe rounder should just be a global? ugh...
-	mid := start.Midpoint(end, geo.Round)
+	mid := start.Midpoint(end)
 
 	along := func(xy, dir geo.XY) int {
 		if dir[0] != 0 {
diff --git a/gim/view.go b/gim/view.go
index ca869cf..07548de 100644
--- a/gim/view.go
+++ b/gim/view.go
@@ -120,8 +120,8 @@ func (view *view) draw(buf *terminal.Buffer) {
 			boxesMr[v] = &b
 
 			bSize := b.rect().Size
-			primBoxLen := bSize.Mul(view.primFlowDir).Len(rounder)
-			secBoxLen := bSize.Mul(view.secFlowDir).Len(rounder)
+			primBoxLen := bSize.Mul(view.primFlowDir).Len()
+			secBoxLen := bSize.Mul(view.secFlowDir).Len()
 			if primBoxLen > maxPrim {
 				maxPrim = primBoxLen
 			}