diff --git a/libc/include/limits.h b/libc/include/limits.h
index b9d4354..471d380 100644
--- a/libc/include/limits.h
+++ b/libc/include/limits.h
@@ -105,9 +105,15 @@
 #define ULONG_LONG_MAX  ULLONG_MAX
 #endif
 
+/* New code should use sysconf(_SC_PAGE_SIZE) instead. */
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 4096
+#endif
 #ifndef PAGESIZE
-#include <asm/page.h>
 #define  PAGESIZE  PAGE_SIZE
 #endif
 
+/* glibc's PAGE_MASK is the bitwise negation of BSD's! TODO: remove? */
+#define PAGE_MASK (~(PAGE_SIZE - 1))
+
 #endif /* !_LIMITS_H_ */