--- src/PatternLayout.cpp.orig      2015-01-14 09:24:32.332489499 +0300
+++ src/PatternLayout.cpp   2015-01-14 09:23:18.162493691 +0300
@@ -24,6 +24,7 @@
 #include <iomanip>
 #include <ctime>
 #include <cstdlib>
+#include <cmath>
 #include "Localtime.hh"
 
 #ifdef LOG4CPP_HAVE_INT64_T