diff --git a/src/parser.lemon b/src/parser.lemon
index 3fc54a7..5904893 100644
--- a/src/parser.lemon
+++ b/src/parser.lemon
@@ -54,8 +54,10 @@
     // Mostly based on the following SO post, but we instead put it in a std::vector
     // https://stackoverflow.com/questions/11705737/expected-token-using-lemon-parser-generator/13010096#13010096
     std::vector<std::string> expectedTokens;
-    int n = sizeof(yyTokenName) / sizeof(yyTokenName[0]);
-    for (int i = 0; i < n; ++i) {
+
+    // we loop over all known tokens, if we exceed our defined tokens we exit
+    // our last defined token is TOKEN_STRING, so we halt when we go past it
+    for (int i = 0; i <= TOKEN_STRING; ++i) {
         int a = yy_find_shift_action(yypParser, (YYCODETYPE)i);
         if (a < YYNSTATE + YYNRULE) expectedTokens.emplace_back(yyTokenName[i]);
     }