diff --git a/include/multipart_parser.hpp b/include/multipart_parser.hpp
index 9adf564..924ee8d 100644
--- a/include/multipart_parser.hpp
+++ b/include/multipart_parser.hpp
@@ -209,6 +209,8 @@
                 }
                 case State::END:
                     break;
+                default:
+                    return ParserError::ERROR_UNEXPECTED_END_OF_INPUT;
             }
         }