diff --git a/pascal.cpp b/pascal.cpp
index 903294a3..1a7cecbe 100644
--- a/pascal.cpp
+++ b/pascal.cpp
@@ -71,14 +71,14 @@ parray<T>::at (size_t idx) const {
 //-----------------------------------------------------------------------------
 template <typename T>
 T*
-parray<T>::begin (void) {
+parray<T>::begin (void) const {
     return data;
 }
 
 
 template <typename T>
 T*
-parray<T>::end (void) {
+parray<T>::end (void) const {
     return data + size;
 }
 
diff --git a/pascal.hpp b/pascal.hpp
index aa8ab931..b79293fb 100644
--- a/pascal.hpp
+++ b/pascal.hpp
@@ -37,8 +37,8 @@ namespace util {
         T& at (size_t idx);
         const T& at (size_t idx) const;
 
-        T* begin (void);
-        T* end   (void);
+        T* begin (void) const;
+        T* end   (void) const;
 
         const T* cbegin (void) const;
         const T* cend   (void) const;