diff --git a/maths.cpp b/maths.cpp
index a65d911e..99b3e30e 100644
--- a/maths.cpp
+++ b/maths.cpp
@@ -27,7 +27,7 @@
 template <typename T>
 T 
 pow2 (T value)
-{ return value * value; }
+    { return value * value; }
 
 template double pow2(double);
 template    int pow2(   int);
@@ -36,7 +36,7 @@ template    int pow2(   int);
 template <typename T>
 double
 rootsquare (T a, T b)
-{ return sqrt (pow2 (a) + pow2 (b)); }
+    { return sqrt (pow2 (a) + pow2 (b)); }
 
 template double rootsquare (double, double);
 template double rootsquare (   int,    int);
@@ -44,13 +44,13 @@ template double rootsquare (   int,    int);
 
 template <>
 bool
-almost_equal (float a, float b)
+almost_equal (const float &a, const float &b)
     { return ieee_single::almost_equal (a, b); }
 
 
 template <>
 bool
-almost_equal (double a, double b)
+almost_equal (const double &a, const double &b)
     { return ieee_double::almost_equal (a, b); }
 
 
diff --git a/maths.hpp b/maths.hpp
index 9c8db6de..2662704e 100644
--- a/maths.hpp
+++ b/maths.hpp
@@ -20,15 +20,17 @@
 #ifndef __MATHS_HPP
 #define __MATHS_HPP
 
+#include "annotations.hpp"
+
 
 template <typename T>
 T 
-pow2 (T value);
+pow2 (T value) pure;
 
 
 template <typename T>
 double
-rootsquare (T a, T b);
+rootsquare (T a, T b) pure;
 
 
 /**
@@ -40,13 +42,13 @@ rootsquare (T a, T b);
 
 template <typename T>
 bool
-almost_equal (T a, T b)
+almost_equal (const T &a, const T &b)
     { return a == b; }
 
 
 template <typename Ta, typename Tb>
 bool
-almost_equal (Ta a, Tb b) {
+almost_equal (const Ta &a, const Tb &b) {
     return almost_equal <decltype(a + b)> (static_cast<decltype(a + b)>(a),
                                            static_cast<decltype(a + b)>(b));
 }
@@ -54,19 +56,19 @@ almost_equal (Ta a, Tb b) {
 
 template <>
 bool
-almost_equal (float a, float b);
+almost_equal (const float &a, const float &b);
 
 
 template <>
 bool
-almost_equal (double a, double b);
+almost_equal (const double &a, const double &b);
 
 
 /// Variadic minimum
 template <typename T>
 const T&
 min (const T &a)
-    { return a ; }
+    { return a; }
 
 
 template <typename T, typename ...Args>
@@ -79,7 +81,7 @@ min (const T &a , const T &b , const Args &...args )
 template <typename T>
 const T&
 max (const T &a)
-    { return a ; }
+    { return a; }
 
 
 template <typename T, typename ...Args>
@@ -88,5 +90,4 @@ max (const T &a , const T &b , const Args &...args )
     { return max ( b > a ? b : a, args...); }
 
 
-
 #endif // __MATHS_HPP
diff --git a/types.hpp b/types.hpp
index e40d07d0..83973cde 100644
--- a/types.hpp
+++ b/types.hpp
@@ -1,6 +1,7 @@
 #ifndef __TYPES_HPP
 #define __TYPES_HPP
 
+#include "annotations.hpp"
 #include "enable_if.hpp"
 
 #include <cstdint>
@@ -124,12 +125,12 @@ size_t elems(T (&)[N])
 
 /// Convert a scalar from host byte order to network byte order
 template <typename T>
-T hton (T);
+T hton (T) pure;
 
 
 /// Convert a scalar from network byte order to host byte order
 template <typename T>
-T ntoh (T);
+T ntoh (T) pure;
 
 
 template <typename T, typename ...Args>