1 files changed, 2 insertions, 0 deletions
diff --git a/engines/sci/engine/grammar.cpp b/engines/sci/engine/grammar.cpp
index 3860f0600a..8c6c93e583 100644
--- a/engines/sci/engine/grammar.cpp
+++ b/engines/sci/engine/grammar.cpp
@@ -51,6 +51,7 @@ struct ParseRule {
 	Common::Array<int> _data;	/**< actual data */
 
 	~ParseRule() {
+		assert(_allocd_rules > 0);
 		--_allocd_rules;
 	}
 
@@ -315,6 +316,7 @@ static void _vocab_free_empty_rule_list(ParseRuleList *list) {
 	if (list->next)
 		_vocab_free_empty_rule_list(list->next);
 	list->next = 0;
+	list->rule = 0;
 	delete list;
 }