diff --git a/include/arena.h b/include/arena.h
index 6a46769..ece1fe5 100644
--- a/include/arena.h
+++ b/include/arena.h
@@ -17,5 +17,6 @@ void* arena_alloc(arena_t* a, size_t len);
 void* arena_calloc(arena_t* a, size_t nmemb, size_t size);
 void* arena_realloc_tail(arena_t* a, size_t len);
 void arena_delete(arena_t* a);
+void arena_free(arena_t* a, void* p);
 
 #endif
diff --git a/src/arena.c b/src/arena.c
index 3171a8b..b304076 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -83,3 +83,11 @@ void arena_delete(arena_t* a)
     arena_reset(a);
     a->data = NULL;
 }
+
+// included for completeness
+void arena_free(arena_t* a, void* p)
+{
+    (void)p;
+    (void)a;
+    return;
+}