diff --git a/srcs/ft_free.c b/srcs/ft_free.c
index cf8cadf..9f1fedb 100644
--- a/srcs/ft_free.c
+++ b/srcs/ft_free.c
@@ -6,7 +6,7 @@
 /*   By: thrieg < thrieg@student.42mulhouse.fr>     +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2025/11/19 15:44:05 by thrieg            #+#    #+#             */
-/*   Updated: 2025/12/08 15:53:31 by thrieg           ###   ########.fr       */
+/*   Updated: 2025/12/08 15:57:17 by thrieg           ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -104,7 +104,7 @@ void free(void *ptr)
 		pthread_mutex_unlock(&g_mut);
 		return; // we didn't allocate this ptr
 	}
-	pthread_mutex_unlock(&g_mut);
 	if (g_state.patern)
-		ft_memset(ptr, g_state.patern ^ 0xFF, header->size); // doesn't need to lock because we only modify the user pointer and the user doesn't have accces to it yet
+		ft_memset(ptr, g_state.patern ^ 0xFF, header->size); // need to lock because this memory can be reallocated from another thread at any time (even before this function returns if we put it outside of lock)
+	pthread_mutex_unlock(&g_mut);
 }