diff --git a/range.cpp b/range.cpp
index 665dee91..7d1cdf9a 100644
--- a/range.cpp
+++ b/range.cpp
@@ -77,6 +77,14 @@ range<T>::clamp (T val) const
     { return std::max (min, std::min (val, max)); }
 
 
+template <typename T>
+T
+range<T>::expand (T val) {
+    min = std::min (min, val);
+    max = std::max (max, val);
+}
+
+
 template <typename T>
 double
 range<T>::normalise (T val) const {
diff --git a/range.hpp b/range.hpp
index 1767197a..5ce67d83 100644
--- a/range.hpp
+++ b/range.hpp
@@ -46,6 +46,9 @@ namespace util {
         /// Return the closest number that falls within the range.
         T clamp (T val) const;
 
+        /// Expand the range to include this value if necessary
+        T expand (T val);
+
         /// Normalise a number to [0, 1] within the range. Does not check bounds.
         double normalise (T val) const;