diff --git a/arch/um/include/os.h b/arch/um/include/os.h
index 07340c8..d246d5a 100644
--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -160,6 +160,7 @@
 extern void os_kill_ptraced_process(int pid, int reap_child);
 extern void os_usr1_process(int pid);
 extern int os_getpid(void);
+extern int os_getpgrp(void);
 
 extern int os_map_memory(void *virt, int fd, unsigned long long off,
 			 unsigned long len, int r, int w, int x);