diff --git a/src/mathed/MathData.cpp b/src/mathed/MathData.cpp
index 5f62d86846..73c1d9db90 100644
--- a/src/mathed/MathData.cpp
+++ b/src/mathed/MathData.cpp
@@ -49,7 +49,9 @@ namespace lyx {
 
 MathData::MathData(Buffer * buf, const_iterator from, const_iterator to)
 	: base_type(from, to), buffer_(buf)
-{}
+{
+	setContentsBuffer();
+}
 
 
 void MathData::setContentsBuffer()