diff --git a/libsolidity/parsing/Token.cpp b/libsolidity/parsing/Token.cpp
index 332d27f7a..4f04ea7ab 100644
--- a/libsolidity/parsing/Token.cpp
+++ b/libsolidity/parsing/Token.cpp
@@ -112,14 +112,10 @@ unsigned Token::extractUnsigned(string::const_iterator const& _begin, string::co
 {
 	try
 	{
-		unsigned short m = stoi(string(_begin, _end));
+		unsigned short m = boost::lexical_cast<unsigned short>(string(_begin, _end));
 		return m;
 	}
-	catch(out_of_range& e)
-	{
-		return 0;
-	}
-	catch (invalid_argument& e)
+	catch(const boost::bad_lexical_cast &)
 	{
 		return 0;
 	}
diff --git a/libsolidity/parsing/Token.h b/libsolidity/parsing/Token.h
index fea80ef77..0e5b594c5 100644
--- a/libsolidity/parsing/Token.h
+++ b/libsolidity/parsing/Token.h
@@ -305,11 +305,7 @@ public:
 	static std::tuple<Token::Value, unsigned short, unsigned short> fromIdentifierOrKeyword(std::string const& _literal);
 
 private:
-	// extractUnsigned provides a safe way to extract numbers, 
-	// if out_of_range error is thrown, they returns 0s, therefore securing 
-	// the variable's identity as an identifier. If an invalid conversion
- 	// error is thrown (usually in the case of grabbing N from a fixed type)
- 	// then a 0 is thrown to purposely ensure that it will declare itself as an identifier
+	// @returns 0 on error (invalid digit or number too large)
 	static unsigned extractUnsigned(std::string::const_iterator const& _begin, std::string::const_iterator const& _end);
 	// @returns the keyword with name @a _name or Token::Identifier of no such keyword exists.
 	static Token::Value keywordByName(std::string const& _name);