diff --git a/cruft/util/region.hpp b/cruft/util/region.hpp
index 36fbf7cb..b36fc726 100644
--- a/cruft/util/region.hpp
+++ b/cruft/util/region.hpp
@@ -401,5 +401,6 @@ namespace cruft {
 
     ///////////////////////////////////////////////////////////////////////////
     template <size_t S, typename T>
-    std::ostream& operator<< (std::ostream&, const cruft::region<S,T>&);
+    std::ostream&
+    operator<< (std::ostream&, const cruft::region<S,T>&);
 }