diff --git a/src/parse.c b/src/parse.c
index 27d0ffc..2b4314b 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -141,6 +141,9 @@ struct ucl_object *ucl_parse_token_atom(struct ucl_object *maybe_atom) {
         case UCL_TYPE_INT:
             atom = ucl_int_create(maybe_atom->integer);
             break;
+        case UCL_TYPE_ERROR:
+        case UCL_TYPE_BUILTIN:
+        case UCL_TYPE_SPECIAL:
         case UCL_TYPE_COUNT:
             assert(false);
     }
@@ -150,6 +153,10 @@ struct ucl_object *ucl_parse_token_atom(struct ucl_object *maybe_atom) {
     return atom;
 }
 
+static void advance_token_iter(struct ucl_object **token_iter) {
+    *token_iter = (*token_iter)->cell.cdr;
+}
+
 static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_iter) {
     // Invariants:
     //  - This function returns NULL if it encounters the first unmatched END_LIST_CHAR
@@ -168,7 +175,7 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
     }
     struct ucl_object *next_sexp = ucl_parse_token_atom(token);
     if (next_sexp != NULL) {
-        *token_iter = (*token_iter)->cell.cdr;
+        advance_token_iter(token_iter);
         return next_sexp;
     }
     assert(token->type == UCL_TYPE_SYMBOL);
@@ -177,7 +184,7 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
         struct ucl_object *list = NULL;
         struct ucl_object **next_node = &list;
         // Consume the START_LIST_CHAR
-        *token_iter = (*token_iter)->cell.cdr;
+        advance_token_iter(token_iter);
         while (1) {
             if (*token_iter == NULL) {
                 // Unexpected end of parsing
@@ -187,7 +194,7 @@ static struct ucl_object *ucl_parse_tokens_recursive(struct ucl_object **token_i
             token = (*token_iter)->cell.car;
 
             if (token->type == UCL_TYPE_SYMBOL && token->symbol[0] == END_LIST_CHAR) {
-                *token_iter = (*token_iter)->cell.cdr;
+                advance_token_iter(token_iter);
                 if (list == NULL) {
                     list = ucl_cell_create(NULL, NULL);
                 }