diff --git a/io.cpp b/io.cpp
index 8c6423b5..f459b99e 100644
--- a/io.cpp
+++ b/io.cpp
@@ -280,13 +280,13 @@ mapped_file::end (void) {
 
 
 const uint8_t*
-mapped_file::begin (void) const {
+mapped_file::cbegin (void) const {
     return data ();
 }
 
 
 const uint8_t*
-mapped_file::end (void) const {
+mapped_file::cend (void) const {
     return data () + size ();
 }
 
diff --git a/io.hpp b/io.hpp
index ae08874e..8cda67d6 100644
--- a/io.hpp
+++ b/io.hpp
@@ -141,8 +141,8 @@ namespace util {
             uint8_t*       begin (void);
             uint8_t*       end   (void);
 
-            const uint8_t* begin (void) const;
-            const uint8_t* end   (void) const;
+            const uint8_t* cbegin (void) const;
+            const uint8_t* cend   (void) const;
     };
 #endif