diff --git a/src/mathed/InsetMathChar.cpp b/src/mathed/InsetMathChar.cpp
index 44ba11d3da..9349663200 100644
--- a/src/mathed/InsetMathChar.cpp
+++ b/src/mathed/InsetMathChar.cpp
@@ -85,6 +85,9 @@ void InsetMathChar::metrics(MetricsInfo & mi, Dimension & dim) const
 		dim.wid += 2 * theFontMetrics(font_).width(' ');
 	lyxerr << "InsetMathChar::metrics: " << dim << endl;
 #endif
+	// Cache the inset dimension. 
+	// FIXME: put the resulting dim in BufferView.
+	dim_ = dim;
 }
 
 
diff --git a/src/mathed/InsetMathChar.h b/src/mathed/InsetMathChar.h
index 3a65841c4f..c1d5b1974a 100644
--- a/src/mathed/InsetMathChar.h
+++ b/src/mathed/InsetMathChar.h
@@ -26,6 +26,8 @@ public:
 	///
 	void metrics(MetricsInfo & mi, Dimension & dim) const;
 	///
+	Dimension const dimension(BufferView const &) const { return dim_; }
+	///
 	void draw(PainterInfo & pi, int x, int y) const;
 	///
 	void metricsT(TextMetricsInfo const & mi, Dimension & dim) const;
@@ -55,6 +57,8 @@ private:
 	char_type char_;
 	/// cached kerning for superscript
 	mutable int kerning_;
+	/// FIXME: move this out to BufferView
+	mutable Dimension dim_;
 };
 
 } // namespace lyx