diff --git a/Makefile.am b/Makefile.am
index c662b7ea..037a6623 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -79,6 +79,7 @@ UTIL_FILES   =		\
     log.ipp		\
     maths.cpp		\
     maths.hpp		\
+    maths.ipp		\
     maths/matrix.cpp	\
     maths/matrix.hpp	\
     maths/polynomial.ipp\
diff --git a/maths.cpp b/maths.cpp
index 4e7f422e..585f21a5 100644
--- a/maths.cpp
+++ b/maths.cpp
@@ -95,15 +95,6 @@ almost_equal (const double &a, const double &b)
     { return ieee_double::almost_equal (a, b); }
 
 
-//-----------------------------------------------------------------------------
-template <typename T>
-typename std::enable_if<std::is_integral<T>::value, T>::type
-round_up (T value, T align) {
-    CHECK_HARD (align > 1);
-    return (value + align - 1) / align;
-}
-
-
 //-----------------------------------------------------------------------------
 template <typename T>
 T
diff --git a/maths.hpp b/maths.hpp
index 4ff39fc7..b831471c 100644
--- a/maths.hpp
+++ b/maths.hpp
@@ -40,9 +40,9 @@ double
 rootsquare (T a, T b) pure;
 
 
-template <typename T>
-T
-round_up (T value, T align) pure;
+template <typename T, typename U>
+typename std::common_type<T, U>::type
+round_up (T value, U align) pure;
 
 
 template <typename T>
@@ -173,4 +173,7 @@ max (const T &a , const T &b , const Args &...args )
 template <typename T>
 int sign (T val);
 
+
+#include "maths.ipp"
+
 #endif // __MATHS_HPP
diff --git a/maths.ipp b/maths.ipp
new file mode 100644
index 00000000..e1da6061
--- /dev/null
+++ b/maths.ipp
@@ -0,0 +1,36 @@
+/*
+ * This file is part of libgim.
+ *
+ * libgim is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later
+ * version.
+ * 
+ * libgim is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with libgim.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright 2014 Danny Robson <danny@nerdcruft.net>
+ */
+
+#ifndef __UTIL_MATHS_IPP
+#define __UTIL_MATHS_IPP
+#else
+#error "Include only once"
+#endif
+
+#include <type_traits>
+
+//-----------------------------------------------------------------------------
+template <typename T, typename U>
+typename std::common_type<T,U>::type
+round_up (T value, U align) {
+    static_assert (std::is_integral<T>::value, "round_up requires integral types");
+    static_assert (std::is_integral<U>::value, "round_up requires integral types");
+
+    return divup (value, align) * align;
+}