diff --git a/src/THcConfigEvtHandler.cxx b/src/THcConfigEvtHandler.cxx
index d69cb3ac20aac941e99ffb9fa4f66ea38f2a0765..c75b7db7b0ae80329001b9b7bafea1a3ecdb99b3 100644
--- a/src/THcConfigEvtHandler.cxx
+++ b/src/THcConfigEvtHandler.cxx
@@ -38,6 +38,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <iostream>
+#include <iomanip>
 
 using namespace std;