diff --git a/src/isdb/FretEfficiency.cpp b/src/isdb/FretEfficiency.cpp
index 28dc4f6762cae79130adb60d23c8d68b619e1e83..828e0ba2424db1fb0728cc9a6741536af6ea837f 100644
--- a/src/isdb/FretEfficiency.cpp
+++ b/src/isdb/FretEfficiency.cpp
@@ -119,7 +119,7 @@ FretEfficiency::FretEfficiency(const ActionOptions&ao):
 
   if(pbc) log.printf("  using periodic boundary conditions\n");
   else    log.printf("  without periodic boundary conditions\n");
-  
+
   log << " Bibliography" << plumed.cite("Bonomi, Camilloni, Bioinformatics, 33, 3999 (2017)") << "\n";
 
   addValueWithDerivatives();