diff --git a/himbaechel/uarch/gatemate/pll.cc b/himbaechel/uarch/gatemate/pll.cc
index 6d0667bd..746c7c05 100644
--- a/himbaechel/uarch/gatemate/pll.cc
+++ b/himbaechel/uarch/gatemate/pll.cc
@@ -18,6 +18,7 @@
  */
 
 #include <boost/algorithm/string.hpp>
+#include <iomanip>
 
 #include "pack.h"