diff --git a/vendor/github.com/gogo/protobuf/proto/extensions.go b/vendor/github.com/gogo/protobuf/proto/extensions.go
index 686bd2a..341c6f5 100644
--- a/vendor/github.com/gogo/protobuf/proto/extensions.go
+++ b/vendor/github.com/gogo/protobuf/proto/extensions.go
@@ -527,6 +527,7 @@
 // SetExtension sets the specified extension of pb to the specified value.
 func SetExtension(pb Message, extension *ExtensionDesc, value interface{}) error {
 	if epb, ok := pb.(extensionsBytes); ok {
+		ClearExtension(pb, extension)
 		newb, err := encodeExtension(extension, value)
 		if err != nil {
 			return err