diff --git a/posts/2015-12-09-modifying-page-tables.md b/posts/2015-12-09-modifying-page-tables.md
index 6de3f973..7c21741d 100644
--- a/posts/2015-12-09-modifying-page-tables.md
+++ b/posts/2015-12-09-modifying-page-tables.md
@@ -458,7 +458,7 @@ pub fn translate(virtual_address: VirtualAddress) -> Option<PhysicalAddress> {
 It uses two functions we haven't defined yet: `translate_page` and `Page::containing_address`. Let's start with the latter:
 
 ```rust
-fn containing_address(address: VirtualAddress) -> Page {
+pub fn containing_address(address: VirtualAddress) -> Page {
     assert!(address < 0x0000_8000_0000_0000 || address >= 0xffff_8000_0000_0000,
         "invalid address: 0x{:x}", address);
     Page { number: address / PAGE_SIZE }