diff --git a/src/mathed/math_mathmlstream.C b/src/mathed/math_mathmlstream.C
index 7bb87bd020..2843602c3c 100644
--- a/src/mathed/math_mathmlstream.C
+++ b/src/mathed/math_mathmlstream.C
@@ -1,4 +1,5 @@
 
+#include "support/LOstream.h"
 #include "math_inset.h"
 #include "math_mathmlstream.h"