diff --git a/src/mathed/math_stringinset.C b/src/mathed/math_stringinset.C
index e9b803f080..a7a7ade2bc 100644
--- a/src/mathed/math_stringinset.C
+++ b/src/mathed/math_stringinset.C
@@ -116,3 +116,10 @@ void MathStringInset::write(WriteStream & os) const
 	else 
 		os << str_;
 }
+
+
+void MathStringInset::validate(LaTeXFeatures & features) const
+{
+	// if (...)
+	//	features.require("amssymb");
+}
diff --git a/src/mathed/math_stringinset.h b/src/mathed/math_stringinset.h
index a3ff6af078..0bf5af1093 100644
--- a/src/mathed/math_stringinset.h
+++ b/src/mathed/math_stringinset.h
@@ -34,6 +34,8 @@ public:
 	string str() const { return str_; }
 	///
 	MathStringInset * asStringInset() { return this; }
+	/// request "external features"
+	void validate(LaTeXFeatures & features) const;
 
 	///
 	void normalize(NormalStream &) const;
diff --git a/src/mathed/math_symbolinset.C b/src/mathed/math_symbolinset.C
index 8b7fc8d546..f2f0f5c6a2 100644
--- a/src/mathed/math_symbolinset.C
+++ b/src/mathed/math_symbolinset.C
@@ -183,3 +183,8 @@ void MathSymbolInset::infoize(std::ostream & os) const
 }
 
 
+void MathSymbolInset::validate(LaTeXFeatures & features) const
+{
+	// if (...)
+	//	features.require("amssymb");
+}
diff --git a/src/mathed/math_symbolinset.h b/src/mathed/math_symbolinset.h
index bb653b220f..e16cf8930c 100644
--- a/src/mathed/math_symbolinset.h
+++ b/src/mathed/math_symbolinset.h
@@ -35,6 +35,8 @@ public:
 	string name() const;
 	///
 	bool match(MathInset *) const;
+	/// request "external features"
+	void validate(LaTeXFeatures & features) const;
 
 	///
 	void normalize(NormalStream &) const;