diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index 18546d8eb78e..36fa286adad5 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -49,7 +49,7 @@
 
 /* memmap is virtually contigious.  */
 #define __pfn_to_page(pfn)	(vmemmap + (pfn))
-#define __page_to_pfn(page)	((page) - vmemmap)
+#define __page_to_pfn(page)	(unsigned long)((page) - vmemmap)
 
 #elif defined(CONFIG_SPARSEMEM)
 /*