diff --git a/modules/mol/alg/src/filter_clashes.cc b/modules/mol/alg/src/filter_clashes.cc
index 113c000ce2d8a87d0f6b182b4687a032b9604477..396ebe39b4370f7fd98742cff96cafe185eb9da3 100644
--- a/modules/mol/alg/src/filter_clashes.cc
+++ b/modules/mol/alg/src/filter_clashes.cc
@@ -19,6 +19,7 @@
 #include <ost/log.hh>
 #include <ost/mol/mol.hh>
 #include <sstream>
+#include <iomanip>
 #include <math.h>
 #include "filter_clashes.hh"
 #include <ost/units.hh>