diff --git a/src/harmonicenergystiffness.hh b/src/harmonicenergystiffness.hh
index 55d6d9b22a4e9c39615e1e5f87b88691c2b3d84f..8ea1ca342043c9d274dfdcc29929d4b3f3924c47 100644
--- a/src/harmonicenergystiffness.hh
+++ b/src/harmonicenergystiffness.hh
@@ -89,7 +89,7 @@ energy(const Entity& element,
 
     }
 
-    return energy;
+    return 0.5 * energy;
 }
 
 #endif