diff --git a/llama/sampling_ext.cpp b/llama/sampling_ext.cpp
index 78b889bd7..1cacd3015 100644
--- a/llama/sampling_ext.cpp
+++ b/llama/sampling_ext.cpp
@@ -114,6 +114,9 @@ void grammar_free(struct llama_grammar *g) {
         if (g->vocab != nullptr) {
             delete g->vocab;
         }
+        if (g->o_vocab != nullptr) {
+                delete g->o_vocab;
+        }
         llama_grammar_free_impl(g);
     }
 }