diff --git a/bfps/cpp/fluid_solver.cpp b/bfps/cpp/fluid_solver.cpp
index 3a6dca4d84f751a5097d21bace03816b70ef4457..1a87b20b2892717d3e466ffbed37a4052bef015a 100644
--- a/bfps/cpp/fluid_solver.cpp
+++ b/bfps/cpp/fluid_solver.cpp
@@ -599,7 +599,7 @@ void fluid_solver<R>::compute_gradient_statistics( \
             AxyAyx = dx_u[tindex+1]*dy_u[tindex+0]; \
             AyzAzy = dy_u[tindex+2]*dz_u[tindex+1]; \
             AzxAxz = dz_u[tindex+0]*dx_u[tindex+2]; \
-            this->rv[1][tindex+1] = - ((AxxAxx + AyyAyy + AzzAzz)/2 - AxyAyx - AyzAzy - AzxAxz); \
+            this->rv[1][tindex+1] = - (AxxAxx + AyyAyy + AzzAzz)/2 - AxyAyx - AyzAzy - AzxAxz; \
             this->rv[1][tindex+2] = - (dx_u[tindex+0]*(AxxAxx/3 + AxyAyx + AzxAxz) + \
                                        dy_u[tindex+1]*(AyyAyy/3 + AxyAyx + AyzAzy) + \
                                        dz_u[tindex+2]*(AzzAzz/3 + AzxAxz + AyzAzy) + \
diff --git a/tox_plain.ini b/tox_plain.ini
index f01ef6218ab4ae9937535a55134439dffb4975ee..3703b995ac42070b2950b27304a22933d6828926 100644
--- a/tox_plain.ini
+++ b/tox_plain.ini
@@ -11,8 +11,8 @@ commands =
     cp -r {toxinidir}/tests {envtmpdir}
     #python tests/test_plain.py -n 256 --run --initialize --ncpu 8 --niter_todo 8 --precision single --wd "data/single"
     python tests/test_plain.py \
-        -n 32 --run --initialize --ncpu 4 \
-        --nparticles 10 --niter_todo 24 \
+        -n 64 --run --initialize --ncpu 4 \
+        --nparticles 0 --niter_todo 96 \
         --precision single --wd "data/single" #\
         #--multiplejob
     #python tests/test_plain.py -n 32 --run --initialize --multiplejob --ncpu 2 --nparticles 16 --niter_todo 64 --precision single --wd "data/single"