diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index 74ea523..9d15e92 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -88,6 +88,7 @@
 
 #if defined(__USE_GNU)
 ssize_t readahead(int, off64_t, size_t);
+int sync_file_range(int, off64_t, off64_t, unsigned int);
 #endif
 
 extern int __open_2(const char*, int);