diff --git a/src/one-body-sample.cc b/src/one-body-sample.cc
index 7d356f56cd8660d5a49cbcf17648870b71fe2113..54b50bc35517c653d6bbc045fab72c66e6e36432 100644
--- a/src/one-body-sample.cc
+++ b/src/one-body-sample.cc
@@ -295,9 +295,7 @@ int main(int argc, char *argv[]) {
     Vector a_initial(fineVertexCount);
     a_initial = 0.0;
     {
-      /* We solve Au + Cv + Ma + Psi(v) = ell, thus
-                                     Ma = - (Au + Cv + Psi(v) - ell)
-      */
+      // We solve Ma = ell - [Au + Cv + Psi(v)]
       Vector accelerationRHS(fineVertexCount);
       {
         accelerationRHS = 0.0;
@@ -305,8 +303,8 @@ int main(int argc, char *argv[]) {
         Arithmetic::addProduct(accelerationRHS, C, v_initial);
         // NOTE: We assume differentiability of Psi at v0 here!
         myGlobalNonlinearity->addGradient(v_initial, accelerationRHS);
-        accelerationRHS -= ell;
         accelerationRHS *= -1.0;
+        accelerationRHS += ell;
       }
       solveLinearProblem(noNodes, M, accelerationRHS, a_initial, MNorm,
                          parset.sub("a0.solver"));