diff --git a/test/stressVector.cxx b/test/stressVector.cxx
index a1501b3924034d45f226e6ef5705779ddbe25abd..37179e28627367ce1e173761b679766d1ccfd9e8 100644
--- a/test/stressVector.cxx
+++ b/test/stressVector.cxx
@@ -192,7 +192,11 @@ double testAddition( const std::vector<V *> & dataV, TStopwatch & tim, double& t
     for (unsigned int j = i +1; j < n; ++j) {
       V & v2 = *(dataV[j]); 
       V v3 = v1 + v2;
-      tot += v3.E();
+      if (i % 1) {
+        tot += v3.E();
+      } else {
+        tot -= v3.E();
+      }
     }
   }
   tim.Stop();
@@ -210,7 +214,11 @@ double testScale( const std::vector<V *> & dataV, TStopwatch & tim, double& t,
     V  & v1 = *(dataV[i]); 
     // scale
     v1 = 2.0*v1;
-    tot += v1.E();
+    if (i % 1) {
+      tot += v1.E();
+    } else {
+      tot -= v1.E();
+    }
   }
   tim.Stop();
   print(tim,s);
@@ -247,7 +255,11 @@ double testDeltaR( const std::vector<V *> & dataV, TStopwatch & tim, double& t,
     for (unsigned int j = i +1; j < n; ++j) {
       V & v2 = *(dataV[j]); 
       double delta = VectorUtil::DeltaR(v1,v2);
-      tot += delta;
+      if (i % 1) {
+        tot += delta;
+      } else {
+        tot -= delta;
+      }
     }
   }
   tim.Stop();