diff --git a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/fieldextractor.go b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/fieldextractor.go
index 549ff48..a4073ab 100644
--- a/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/fieldextractor.go
+++ b/vendor/github.com/grpc-ecosystem/go-grpc-middleware/tags/fieldextractor.go
@@ -64,10 +64,10 @@
 		field := v.Field(i)
 		kind := field.Kind()
 		// Only recurse down direct pointers, which should only be to nested structs.
-		if kind == reflect.Ptr {
+		if (kind == reflect.Ptr || kind == reflect.Interface) && field.CanInterface() {
 			reflectMessageTags(field.Interface(), existingMap, tagName)
 		}
-		// In case of arrays/splices (repeated fields) go down to the concrete type.
+		// In case of arrays/slices (repeated fields) go down to the concrete type.
 		if kind == reflect.Array || kind == reflect.Slice {
 			if field.Len() == 0 {
 				continue