diff --git a/Parser/pegen_errors.c b/Parser/pegen_errors.c
index bffae8532ca..f348ac3000d 100644
--- a/Parser/pegen_errors.c
+++ b/Parser/pegen_errors.c
@@ -254,6 +254,9 @@ get_error_line_from_tokenizer_buffers(Parser *p, Py_ssize_t lineno)
 
     for (int i = 0; i < relative_lineno - 1; i++) {
         char *new_line = strchr(cur_line, '\n') + 1;
+        // The assert is here for debug builds but the conditional that
+        // follows is there so in release builds we do not crash at the cost
+        // to report a potentially wrong line.
         assert(new_line != NULL && new_line < p->tok->inp);
         if (new_line == NULL || new_line >= p->tok->inp) {
             break;