diff --git a/src/mathed/InsetMathFontOld.h b/src/mathed/InsetMathFontOld.h
index 734fabc3e7..3cdf775602 100644
--- a/src/mathed/InsetMathFontOld.h
+++ b/src/mathed/InsetMathFontOld.h
@@ -43,6 +43,8 @@ public:
 	void normalize(NormalStream &) const;
 	///
 	void infoize(odocstream & os) const;
+	///
+	int kerning() const { return cell(0).kerning(); }
 
 private:
 	virtual std::auto_ptr<InsetBase> doClone() const;
diff --git a/src/mathed/InsetMathUnknown.C b/src/mathed/InsetMathUnknown.C
index 302c913829..b99e5e6404 100644
--- a/src/mathed/InsetMathUnknown.C
+++ b/src/mathed/InsetMathUnknown.C
@@ -56,6 +56,8 @@ void InsetMathUnknown::normalize(NormalStream & os) const
 bool InsetMathUnknown::metrics(MetricsInfo & mi, Dimension & dim) const
 {
 	mathed_string_dim(mi.base.font, name_, dim);
+	docstring::const_reverse_iterator rit = name_.rbegin();
+	kerning_ = mathed_char_kerning(mi.base.font, *rit);
 	if (dim_ == dim)
 		return false;
 	dim_ = dim;
diff --git a/src/mathed/InsetMathUnknown.h b/src/mathed/InsetMathUnknown.h
index d1ab2bc50a..9d30e19807 100644
--- a/src/mathed/InsetMathUnknown.h
+++ b/src/mathed/InsetMathUnknown.h
@@ -51,6 +51,8 @@ public:
 	void finalize();
 	///
 	bool final() const;
+	///
+	int kerning() const { return kerning_; }
 private:
 	virtual std::auto_ptr<InsetBase> doClone() const;
 	///
@@ -59,6 +61,8 @@ private:
 	bool final_;
 	///
 	bool black_;
+	///
+	mutable int kerning_;
 };