diff --git a/src/mathed/InsetMathNumber.cpp b/src/mathed/InsetMathNumber.cpp
index c9ae470dec..45e73220fc 100644
--- a/src/mathed/InsetMathNumber.cpp
+++ b/src/mathed/InsetMathNumber.cpp
@@ -76,6 +76,12 @@ void InsetMathNumber::mathmlize(MathStream & os) const
 }
 
 
+void InsetMathNumber::htmlize(HtmlStream & os) const
+{
+	os << str_;
+}
+
+
 void InsetMathNumber::write(WriteStream & os) const
 {
 	os << str_;
diff --git a/src/mathed/InsetMathNumber.h b/src/mathed/InsetMathNumber.h
index a6ca9dae29..68d08bd315 100644
--- a/src/mathed/InsetMathNumber.h
+++ b/src/mathed/InsetMathNumber.h
@@ -45,6 +45,8 @@ public:
 	///
 	void mathmlize(MathStream &) const;
 	///
+	void htmlize(HtmlStream &) const;
+	///
 	void write(WriteStream & os) const;
 	///
 	InsetCode lyxCode() const { return MATH_NUMBER_CODE; }