diff --git a/src/network/private/approx8.cpp b/src/network/private/approx8.cpp
index c80e3ac3..8d08ff5e 100644
--- a/src/network/private/approx8.cpp
+++ b/src/network/private/approx8.cpp
@@ -421,7 +421,7 @@ namespace nnApprox8{
 		for (int i=0; i<Net::niso; i++) { 
 			enuc += Net::mion[i]*dydt[i]; 
 		}
-		dydt[Net::iener] = enuc*avo*clight*clight;
+		dydt[Net::iener] = -enuc*avo*clight*clight;
 	} 
 
 	nuclearNetwork::NetOut Approx8Network::evaluate(const nuclearNetwork::NetIn &netIn) {
diff --git a/tests/network/approx8Test.cpp b/tests/network/approx8Test.cpp
index a944c1f3..acebae89 100644
--- a/tests/network/approx8Test.cpp
+++ b/tests/network/approx8Test.cpp
@@ -46,5 +46,5 @@ TEST_F(approx8Test, evaluate) {
 
     EXPECT_DOUBLE_EQ(netOut.composition[nnApprox8::Net::ih1], 0.50166260916650918);
     EXPECT_DOUBLE_EQ(netOut.composition[nnApprox8::Net::ihe4],0.48172270591286032);
-    EXPECT_DOUBLE_EQ(netOut.energy, -1.6433049870528356e+18);
+    EXPECT_DOUBLE_EQ(netOut.energy, 1.6433049870528356e+18);
 }