diff --git a/src/network/private/approx8.cpp b/src/network/private/approx8.cpp
index 8d08ff5..c9e597a 100644
--- a/src/network/private/approx8.cpp
+++ b/src/network/private/approx8.cpp
@@ -325,7 +325,7 @@ namespace nnApprox8{
             for (int i=0; i<Net::niso; i++) { 
 				J(Net::iener,j) += J(i,j)*Net::mion[i]; 
 			}
-            J(Net::iener,j) *= avo*clight*clight;
+            J(Net::iener,j) *= -avo*clight*clight;
         }
     }