diff --git a/include/linux/sys.h b/include/linux/sys.h
index 8c92ab3e1792a060b3d760c7bcf7766d945e72d9..532b87be17f0a111c66ee25a701dd47f9e8a658d 100644
--- a/include/linux/sys.h
+++ b/include/linux/sys.h
@@ -58,7 +58,7 @@ extern int sys_mpx();
 //extern int sys_setpgid();
 extern int sys_ulimit();
 extern int sys_uname();
-//extern int sys_umask();
+extern int sys_umask();
 extern int sys_chroot();
 //extern int sys_ustat();
 //extern int sys_dup2();
@@ -156,7 +156,7 @@ fn_ptr sys_call_table[] = {
     sys_ulimit,
 
     sys_uname,
-    0, //    sys_umask,
+    sys_umask,
     sys_chroot,
     0, //    sys_ustat,
     0, //    sys_dup2,
diff --git a/include/unistd.h b/include/unistd.h
index f180a18082f8c28a90ac450656320ef2bd9b2ed8..f2436f25520185aa57967c4e296e29c42ebefa8a 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -168,6 +168,7 @@ int lseek(int fildes, off_t offset, int origin);
 int rmdir(const char* pathname);
 
 time_t time(time_t * tloc);
+mode_t umask(mode_t mask);
 int uname(struct utsname * name);
 
 #endif
diff --git a/kernel/sys.c b/kernel/sys.c
index e1145959c8e7258dc3f94facf280e4d4d9663ade..6e29cda4616185e899035496d7e58cb257091d97 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -102,3 +102,10 @@ int sys_uname(struct utsname * name) {
     return 0;
 }
 
+int sys_umask(int mask) {
+    int old = current->umask;
+
+    current->umask = mask & 0777;
+    return (old);
+}
+