diff --git a/src/headers/lex.hpp b/src/headers/lex.hpp
index e00b19d..baed249 100644
--- a/src/headers/lex.hpp
+++ b/src/headers/lex.hpp
@@ -19,6 +19,15 @@ struct tok {
     const type toktype;
     const std::string toktext;
     const unsigned long line;
+    tok& operator=(const tok& other) {
+        if (this != &other) {
+            const_cast<type&>(toktype) = other.toktype;
+            const_cast<std::string&>(toktext) = other.toktext;
+            const_cast<unsigned long&>(line) = other.line;
+        }
+        return *this;
+    }
+    tok(): toktype(UNEXPECTED), toktext(), line(0) {};
     tok(const type& Type, std::string_view Text, const decltype(line)& line = 0): toktype(Type), toktext(Text), line(line) {}
     explicit tok(const type& Type, const decltype(line)& line = 0): tok(Type, std::string(1, Type), line) {};
     friend std::ostream& operator<<(std::ostream& output, const tok& it) { return output << it.toktext; }