diff --git a/05-JurrasicPark/main.c b/05-JurrasicPark/main.c
index b66b701..5bee2f0 100644
--- a/05-JurrasicPark/main.c
+++ b/05-JurrasicPark/main.c
@@ -27,7 +27,7 @@
 #include "park.h"
 
 // Jurassic Park
-extern int begin;
+extern volatile int begin;
 extern JPARK myPark;
 extern pthread_mutex_t parkMutex;            // mutex park variable access
 extern pthread_mutex_t fillSeat[NUM_CARS];   // (signal) seat ready to fill
@@ -55,4 +55,4 @@ int main(int argc, char *argv[])
 
     pthread_join(parkTask, NULL);
     return 0;
-}
+}
\ No newline at end of file