diff --git a/freetype/freetype.go b/freetype/freetype.go
index ff94b44..cd82f2d 100644
--- a/freetype/freetype.go
+++ b/freetype/freetype.go
@@ -9,11 +9,11 @@
 package freetype
 
 import (
+	"errors"
 	"freetype-go.googlecode.com/hg/freetype/raster"
 	"freetype-go.googlecode.com/hg/freetype/truetype"
 	"image"
 	"image/draw"
-	"os"
 )
 
 // These constants determine the size of the glyph cache. The cache is keyed
@@ -39,7 +39,7 @@ type cacheEntry struct {
 // ParseFont just calls the Parse function from the freetype/truetype package.
 // It is provided here so that code that imports this package doesn't need
 // to also include the freetype/truetype package.
-func ParseFont(b []byte) (*truetype.Font, os.Error) {
+func ParseFont(b []byte) (*truetype.Font, error) {
 	return truetype.Parse(b)
 }
 
@@ -151,7 +151,7 @@ func (c *Context) drawContour(ps []truetype.Point, dx, dy raster.Fix32) {
 // rasterize returns the glyph mask and integer-pixel offset to render the
 // given glyph at the given sub-pixel offsets.
 // The 24.8 fixed point arguments fx and fy must be in the range [0, 1).
-func (c *Context) rasterize(glyph truetype.Index, fx, fy raster.Fix32) (*image.Alpha, image.Point, os.Error) {
+func (c *Context) rasterize(glyph truetype.Index, fx, fy raster.Fix32) (*image.Alpha, image.Point, error) {
 	if err := c.glyphBuf.Load(c.font, glyph); err != nil {
 		return nil, image.ZP, err
 	}
@@ -161,7 +161,7 @@ func (c *Context) rasterize(glyph truetype.Index, fx, fy raster.Fix32) (*image.A
 	xmax := int(fx+c.FUnitToFix32(+int(c.glyphBuf.B.XMax))+0xff) >> 8
 	ymax := int(fy+c.FUnitToFix32(-int(c.glyphBuf.B.YMin))+0xff) >> 8
 	if xmin > xmax || ymin > ymax {
-		return nil, image.ZP, os.NewError("freetype: negative sized glyph")
+		return nil, image.ZP, errors.New("freetype: negative sized glyph")
 	}
 	// A TrueType's glyph's nodes can have negative co-ordinates, but the
 	// rasterizer clips anything left of x=0 or above y=0. xmin and ymin
@@ -185,7 +185,7 @@ func (c *Context) rasterize(glyph truetype.Index, fx, fy raster.Fix32) (*image.A
 // glyph returns the glyph mask and integer-pixel offset to render the given
 // glyph at the given sub-pixel point. It is a cache for the rasterize method.
 // Unlike rasterize, p's co-ordinates do not have to be in the range [0, 1).
-func (c *Context) glyph(glyph truetype.Index, p raster.Point) (*image.Alpha, image.Point, os.Error) {
+func (c *Context) glyph(glyph truetype.Index, p raster.Point) (*image.Alpha, image.Point, error) {
 	// Split p.X and p.Y into their integer and fractional parts.
 	ix, fx := int(p.X>>8), p.X&0xff
 	iy, fy := int(p.Y>>8), p.Y&0xff
@@ -214,9 +214,9 @@ func (c *Context) glyph(glyph truetype.Index, p raster.Point) (*image.Alpha, ima
 // For example, drawing a string that starts with a 'J' in an italic font may
 // affect pixels below and left of the point.
 // p is a raster.Point and can therefore represent sub-pixel positions.
-func (c *Context) DrawString(s string, p raster.Point) (raster.Point, os.Error) {
+func (c *Context) DrawString(s string, p raster.Point) (raster.Point, error) {
 	if c.font == nil {
-		return raster.Point{}, os.NewError("freetype: DrawText called with a nil font")
+		return raster.Point{}, errors.New("freetype: DrawText called with a nil font")
 	}
 	prev, hasPrev := truetype.Index(0), false
 	for _, rune := range s {
diff --git a/freetype/truetype/truetype.go b/freetype/truetype/truetype.go
index d1eecde..ffec56e 100644
--- a/freetype/truetype/truetype.go
+++ b/freetype/truetype/truetype.go
@@ -15,7 +15,6 @@ package truetype
 
 import (
 	"fmt"
-	"os"
 )
 
 // An Index is a Font's index of a Unicode code point.
@@ -36,7 +35,7 @@ type HMetric struct {
 // A FormatError reports that the input is not a valid TrueType font.
 type FormatError string
 
-func (e FormatError) String() string {
+func (e FormatError) Error() string {
 	return "freetype: invalid TrueType format: " + string(e)
 }
 
@@ -44,7 +43,7 @@ func (e FormatError) String() string {
 // TrueType feature.
 type UnsupportedError string
 
-func (e UnsupportedError) String() string {
+func (e UnsupportedError) Error() string {
 	return "freetype: unsupported TrueType feature: " + string(e)
 }
 
@@ -78,7 +77,7 @@ func (d *data) skip(n int) {
 }
 
 // readTable returns a slice of the TTF data given by a table's directory entry.
-func readTable(ttf []byte, offsetLength []byte) ([]byte, os.Error) {
+func readTable(ttf []byte, offsetLength []byte) ([]byte, error) {
 	d := data(offsetLength)
 	offset := int(d.u32())
 	if offset < 0 || offset > 1<<24 || offset > len(ttf) {
@@ -117,7 +116,7 @@ type Font struct {
 	bounds                  Bounds
 }
 
-func (f *Font) parseCmap() os.Error {
+func (f *Font) parseCmap() error {
 	const (
 		cmapFormat4         = 4
 		languageIndependent = 0
@@ -192,7 +191,7 @@ func (f *Font) parseCmap() os.Error {
 	return nil
 }
 
-func (f *Font) parseHead() os.Error {
+func (f *Font) parseHead() error {
 	if len(f.head) != 54 {
 		return FormatError(fmt.Sprintf("bad head length: %d", len(f.head)))
 	}
@@ -215,7 +214,7 @@ func (f *Font) parseHead() os.Error {
 	return nil
 }
 
-func (f *Font) parseHhea() os.Error {
+func (f *Font) parseHhea() error {
 	if len(f.hhea) != 36 {
 		return FormatError(fmt.Sprintf("bad hhea length: %d", len(f.hhea)))
 	}
@@ -227,7 +226,7 @@ func (f *Font) parseHhea() os.Error {
 	return nil
 }
 
-func (f *Font) parseKern() os.Error {
+func (f *Font) parseKern() error {
 	// Apple's TrueType documentation (http://developer.apple.com/fonts/TTRefMan/RM06/Chap6kern.html) says:
 	// "Previous versions of the 'kern' table defined both the version and nTables fields in the header
 	// as UInt16 values and not UInt32 values. Use of the older format on the Mac OS is discouraged
@@ -269,7 +268,7 @@ func (f *Font) parseKern() os.Error {
 	return nil
 }
 
-func (f *Font) parseMaxp() os.Error {
+func (f *Font) parseMaxp() error {
 	if len(f.maxp) != 32 {
 		return FormatError(fmt.Sprintf("bad maxp length: %d", len(f.maxp)))
 	}
@@ -348,7 +347,7 @@ func (f *Font) Kerning(i0, i1 Index) int16 {
 }
 
 // Parse returns a new Font for the given TTF data.
-func Parse(ttf []byte) (font *Font, err os.Error) {
+func Parse(ttf []byte) (font *Font, err error) {
 	if len(ttf) < 12 {
 		err = FormatError("TTF data is too short")
 		return
@@ -503,7 +502,7 @@ func (g *GlyphBuf) decodeCoords(d data, np0 int) {
 
 // Load loads a glyph's contours from a Font, overwriting any previously
 // loaded contours for this GlyphBuf.
-func (g *GlyphBuf) Load(f *Font, i Index) os.Error {
+func (g *GlyphBuf) Load(f *Font, i Index) error {
 	// Reset the GlyphBuf.
 	g.B = Bounds{}
 	g.Point = g.Point[0:0]
@@ -512,7 +511,7 @@ func (g *GlyphBuf) Load(f *Font, i Index) os.Error {
 }
 
 // loadCompound loads a glyph that is composed of other glyphs.
-func (g *GlyphBuf) loadCompound(f *Font, d data, recursion int) os.Error {
+func (g *GlyphBuf) loadCompound(f *Font, d data, recursion int) error {
 	// Flags for decoding a compound glyph. These flags are documented at
 	// http://developer.apple.com/fonts/TTRefMan/RM06/Chap6glyf.html.
 	const (
@@ -562,7 +561,7 @@ func (g *GlyphBuf) loadCompound(f *Font, d data, recursion int) os.Error {
 }
 
 // load appends a glyph's contours to this GlyphBuf.
-func (g *GlyphBuf) load(f *Font, i Index, recursion int) os.Error {
+func (g *GlyphBuf) load(f *Font, i Index, recursion int) error {
 	if recursion >= 4 {
 		return UnsupportedError("excessive compound glyph recursion")
 	}