diff --git a/src/osgPlugins/stl/ReaderWriterSTL.cpp b/src/osgPlugins/stl/ReaderWriterSTL.cpp
index 608f82cd0..5f8972325 100644
--- a/src/osgPlugins/stl/ReaderWriterSTL.cpp
+++ b/src/osgPlugins/stl/ReaderWriterSTL.cpp
@@ -45,6 +45,7 @@
 
 #include <string.h>
 #include <memory>
+#include <iomanip>
 
 struct STLOptionsStruct {
     bool smooth;