diff --git a/log.ipp b/log.ipp
index 9c70b49e..3419d254 100644
--- a/log.ipp
+++ b/log.ipp
@@ -17,11 +17,18 @@
  * Copyright 2012 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef __UTIL_LOG_IPP
+#ifdef __UTIL_LOG_IPP
+#error Double inclusion of util/log.ipp
+#endif
+
 #define __UTIL_LOG_IPP
 
+
+//-----------------------------------------------------------------------------
 #include <boost/format.hpp>
 
+
+//-----------------------------------------------------------------------------
 namespace util {
     namespace detail  {
         void
@@ -39,5 +46,3 @@ namespace util {
         { detail::log (l, std::move (boost::format (format)), _tail...); }
 }
 
-
-#endif
diff --git a/maths/polynomial.ipp b/maths/polynomial.ipp
index 6bbe2137..37ccb23a 100644
--- a/maths/polynomial.ipp
+++ b/maths/polynomial.ipp
@@ -17,6 +17,14 @@
  * Copyright 2010 Danny Robson <danny@nerdcruft.net>
  */
 
+#ifdef __UTIL_MATHS_POLYNOMIAL_IPP
+#error Double includion of util/maths/polynomial.hpp
+#endif
+
+#define __UTIL_MATHS_POLYNOMIAL_IPP
+
+
+//-----------------------------------------------------------------------------
 template <typename T, size_t N>
 T
 maths::polynomial<T,N>::eval (T x) const {
diff --git a/random.ipp b/random.ipp
index d72d9435..9120ad2d 100644
--- a/random.ipp
+++ b/random.ipp
@@ -17,9 +17,14 @@
  * Copyright 2010 Danny Robson <danny@nerdcruft.net>
  */
 
-#ifndef __UTIL_RANDOM_IPP
+#ifdef __UTIL_RANDOM_IPP
+#error Double inclusion of util/random.ipp
+#endif
+
 #define __UTIL_RANDOM_IPP
 
+
+//-----------------------------------------------------------------------------
 namespace util {
     template <typename T, size_t N>
     T* randomise (T (&array)[N]) {
@@ -29,4 +34,3 @@ namespace util {
     }
 }
 
-#endif