diff --git a/src/lexer.h b/src/lexer.h
index ffe5d5f3..270c7c1d 100644
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -38,7 +38,13 @@ constexpr TokenIndex TK(const char token[]) {
         while(*i && *j && *i == *j) { i++; j++;}
         if(*i == *j) return k;
     }
+#ifdef __GNUC__
+    // for old version of gcc, it is not smart enough to ignore FATAL_ERROR()
+    // so we must do a normal return
+    return 255;
+#else
     FATAL_ERROR();
+#endif
 }
 
 #define TK_STR(t) kTokens[t]
@@ -508,4 +514,4 @@ struct Lexer {
     }
 };
 
-} // namespace pkpy
\ No newline at end of file
+} // namespace pkpy