diff --git a/SharedData/SharedData.c b/SharedData/SharedData.c
index 7313701..b0661cd 100644
--- a/SharedData/SharedData.c
+++ b/SharedData/SharedData.c
@@ -41,8 +41,10 @@ void start_all_threads_SharedData(THIS(SharedData)){
 			this->threads_nb = residents->get_size(residents) + visitors->get_size(visitors) + ELEVATOR_NB;
 			this->threads = malloc_or_die(sizeof(pthread_t*) * this->threads_nb);
 
-			for (i=0; i < this->threads_nb; i++)
+			for (i=0; i < this->threads_nb; i++){
+				this->threads[i] = NULL;
 				this->threads[i] = malloc_or_die(sizeof(pthread_t));
+			}
 
 			pthread_mutex_lock(&this->mutex_active_passengers);
 			pthread_mutex_lock(&this->mutex_threads);
@@ -95,7 +97,7 @@ void _free__SharedData(THIS(SharedData)){
 	if (this->threads != NULL){
 		for (i=0; i<this->threads_nb; i++) {
 			if (this->threads[i] != NULL) {
-				printf("Quitting thread %d\n", (int) this->threads[i]);
+				printf("Quitting thread %d\n", (*(int*) this->threads[i]));
 				pthread_kill(*this->threads[i], SIGUSR1);
 			}
 			free(this->threads[i]);
@@ -107,6 +109,8 @@ void _free__SharedData(THIS(SharedData)){
 
 	pthread_mutex_unlock(&this->mutex_active_passengers);
 	pthread_mutex_destroy(&this->mutex_active_passengers);
+	pthread_mutex_unlock(&this->mutex_threads);
+	pthread_mutex_destroy(&this->mutex_threads);
 
 	free(this);
 }