--- CMakeLists.txt.orig	2013-03-01 08:05:02.371999000 +0100
+++ CMakeLists.txt	2013-03-09 12:19:03.000000000 +0100
@@ -36,6 +36,9 @@
     endif()
 endif(NOT GMP_FOUND)
 
+find_package (MPFR REQUIRED)
+add_definitions (-DKNUMBER_USE_MPFR)
+
 include(CheckTypeSize)
 include(CheckFunctionExists)
 include(CheckIncludeFiles)