diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 8d47566e..374033f8 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -196,6 +196,7 @@ void				swab(const void* __restrict src, void* __restrict dest, ssize_t nbytes);
 int					symlink(const char* path1, const char* path2);
 int					symlinkat(const char* path1, int fd, const char* path2);
 void				sync(void);
+void				syncsync(int should_block);
 long				sysconf(int name);
 pid_t				tcgetpgrp(int fildes);
 int					tcsetpgrp(int fildes, pid_t pgid_id);
diff --git a/libc/unistd.cpp b/libc/unistd.cpp
index c6eec388..b334b4d4 100644
--- a/libc/unistd.cpp
+++ b/libc/unistd.cpp
@@ -202,7 +202,12 @@ int chdir(const char* path)
 
 void sync(void)
 {
-	syscall(SYS_SYNC);
+	syscall(SYS_SYNC, false);
+}
+
+void syncsync(int should_block)
+{
+	syscall(SYS_SYNC, should_block);
 }
 
 pid_t getpid(void)