diff --git a/font/sfnt/sfnt.go b/font/sfnt/sfnt.go
index b6045e7..fc782d8 100644
--- a/font/sfnt/sfnt.go
+++ b/font/sfnt/sfnt.go
@@ -1522,7 +1522,7 @@ func (f *Font) GlyphBounds(b *Buffer, x GlyphIndex, ppem fixed.Int26_6, h font.H
                x = n
        }
 
-       buf, err := b.view(&f.src, int(f.hmtx.offset)+int(4*x), 2)
+       buf, err := b.view(&f.src, int(f.hmtx.offset)+int(x)*4, 2)
        if err != nil {
                return fixed.Rectangle26_6{}, 0, err
        }
@@ -1602,7 +1602,7 @@ func (f *Font) GlyphAdvance(b *Buffer, x GlyphIndex, ppem fixed.Int26_6, h font.
                x = n
        }
 
-       buf, err := b.view(&f.src, int(f.hmtx.offset)+int(4*x), 2)
+       buf, err := b.view(&f.src, int(f.hmtx.offset)+int(x)*4, 2)
        if err != nil {
                return 0, err
        }