diff --git a/libgo/go/cmd/cgo/out.go b/libgo/go/cmd/cgo/out.go
index 7282933..97886e1 100644
--- a/libgo/go/cmd/cgo/out.go
+++ b/libgo/go/cmd/cgo/out.go
@@ -1318,8 +1318,10 @@
 	for _, c := range []byte(ppath) {
 		switch {
 		case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z',
-			'0' <= c && c <= '9', c == '_', c == '.':
+			'0' <= c && c <= '9', c == '_':
 			bsl = append(bsl, c)
+		case c == '.':
+			bsl = append(bsl, ".x2e"...)
 		default:
 			changed = true
 			encbytes := []byte(fmt.Sprintf("..z%02x", c))