diff --git a/libc/include/sys/param.h b/libc/include/sys/param.h
index e64d6ce..5d2248f 100644
--- a/libc/include/sys/param.h
+++ b/libc/include/sys/param.h
@@ -31,6 +31,8 @@
 #include <limits.h>
 #include <linux/param.h>
 
+#define DEV_BSIZE 512
+
 #define MAXPATHLEN  PATH_MAX
 #define MAXSYMLINKS 8