diff --git a/source/uapi/monitor_user.c b/source/uapi/monitor_user.c
index be78e5a..4188136 100644
--- a/source/uapi/monitor_user.c
+++ b/source/uapi/monitor_user.c
@@ -2,6 +2,7 @@
 #include <fcntl.h>
 #include <stdio.h>
 #include <sys/ioctl.h>
+#include <sys/syscall.h>
 #include <unistd.h>
 
 #define DEVICE "/dev/variable_monitor"
@@ -43,11 +44,10 @@ int cancel_watch() {
   return 0;
 }
 
-void init_watch_arg(watch_arg *wg, char *name, void *ptr,
-                           int length_byte, long long threshold,
-                           unsigned char is_unsigned,
-                           unsigned char above_threshold, unsigned long time_ns){
-  wg->task_id = getpid();
+void init_watch_arg(watch_arg *wg, char *name, void *ptr, int length_byte,
+                    long long threshold, unsigned char is_unsigned,
+                    unsigned char above_threshold, unsigned long time_ns) {
+  wg->task_id = gettid();
   strncpy(wg->name, name, (MAX_NAME_LEN + 1));
   wg->ptr = ptr;
   wg->length_byte = length_byte;