diff --git a/font/sfnt/cmap.go b/font/sfnt/cmap.go
index 55b4ead..2035ea9 100644
--- a/font/sfnt/cmap.go
+++ b/font/sfnt/cmap.go
@@ -186,6 +186,9 @@
 				if offset > indexesLength || offset+2 > indexesLength {
 					return 0, errInvalidCmapTable
 				}
+				if b == nil {
+					b = &Buffer{}
+				}
 				x, err := b.view(&f.src, int(indexesBase+offset), 2)
 				if err != nil {
 					return 0, err