diff --git a/range.cpp b/range.cpp
index 7d1cdf9a..29463d5d 100644
--- a/range.cpp
+++ b/range.cpp
@@ -78,7 +78,7 @@ range<T>::clamp (T val) const
 
 
 template <typename T>
-T
+void
 range<T>::expand (T val) {
     min = std::min (min, val);
     max = std::max (max, val);
diff --git a/range.hpp b/range.hpp
index 5ce67d83..3a809f1f 100644
--- a/range.hpp
+++ b/range.hpp
@@ -47,8 +47,7 @@ namespace util {
         T clamp (T val) const;
 
         /// Expand the range to include this value if necessary
-        T expand (T val);
-
+        void expand (T val);
         /// Normalise a number to [0, 1] within the range. Does not check bounds.
         double normalise (T val) const;