diff --git a/NPLib/Detectors/BigRIPS/TBigRIPSReco.cxx b/NPLib/Detectors/BigRIPS/TBigRIPSReco.cxx
index 8b9c3219e143e896946d5cc53e31918d3342231c..60e7955b10d63e7586b7d7bef9aad59d58a8615f 100644
--- a/NPLib/Detectors/BigRIPS/TBigRIPSReco.cxx
+++ b/NPLib/Detectors/BigRIPS/TBigRIPSReco.cxx
@@ -1,5 +1,5 @@
 #include "TBigRIPSReco.h"
-
+#include <cmath>
 TBigRIPSReco::TBigRIPSReco(){Init();}
 TBigRIPSReco::~TBigRIPSReco(){Clear();}