diff --git a/include/kerndat.h b/include/kerndat.h
index de86dba2b..2b3856ccb 100644
--- a/include/kerndat.h
+++ b/include/kerndat.h
@@ -19,6 +19,6 @@ extern int tcp_max_wshare;
 extern int tcp_max_rshare;
 
 extern int kern_last_cap;
-extern unsigned long zero_page_pfn;
+extern u64 zero_page_pfn;
 
 #endif /* __CR_KERNDAT_H__ */
diff --git a/kerndat.c b/kerndat.c
index 204f6fa53..00eda2eb9 100644
--- a/kerndat.c
+++ b/kerndat.c
@@ -154,7 +154,7 @@ out:
 }
 
 /* The page frame number (PFN) is constant for the zero page */
-unsigned long zero_page_pfn;
+u64 zero_page_pfn;
 
 static int init_zero_page_pfn()
 {