diff --git a/configure.ac b/configure.ac
index bc43b89f..1155dd6b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -62,6 +62,8 @@ if test a$occon = atrue ; then
 	AC_CHECK_HEADER([iostream.h],[OCC_FLAGS="$OCCFLAGS -DHAVE_IOSTREAM_H"])
 	AC_CHECK_HEADER([limits],[OCCFLAGS="$OCCFLAGS -DHAVE_LIMITS"])
 	AC_CHECK_HEADER([limits.h],[OCCFLAGS="$OCCFLAGS -DHAVE_LIMITS_H"])
+	AC_CHECK_HEADER([iomanip],[OCCFLAGS="$OCCFLAGS -DHAVE_IOMANIP"])
+	AC_CHECK_HEADER([iomanip.h],[OCCFLAGS="$OCCFLAGS -DHAVE_IOMANIP_H"])
 
 
 	echo "OCCFLAGS = $OCCFLAGS"