diff --git a/solvers/NBody/mobility.h b/solvers/NBody/mobility.h
index e4f1bfa..6ead265 100644
--- a/solvers/NBody/mobility.h
+++ b/solvers/NBody/mobility.h
@@ -30,8 +30,8 @@ class NBody : public libmobility::Mobility {
   real wallHeight; // location of the wall in z
 
   // Batched functionality configuration
-  int Nbatch;
-  int NperBatch;
+  int Nbatch = -1;
+  int NperBatch = -1;
 
   std::mt19937 rng;
 
diff --git a/solvers/PSE/mobility.h b/solvers/PSE/mobility.h
index 02e8749..aba0601 100644
--- a/solvers/PSE/mobility.h
+++ b/solvers/PSE/mobility.h
@@ -4,6 +4,7 @@
 #include "extra/uammd_interface.h"
 #include <MobilityInterface/MobilityInterface.h>
 #include <cmath>
+#include <optional>
 #include <type_traits>
 #include <vector>
 
@@ -50,7 +51,8 @@ class PSE : public libmobility::Mobility {
   }
 
   struct PSEParameters {
-    real psi, Lx, Ly, Lz, shearStrain;
+    real psi, Lx, Ly, Lz;
+    std::optional<real> shearStrain = std::nullopt;
   };
 
   void setParametersPSE(PSEParameters i_par) {
@@ -58,7 +60,7 @@ class PSE : public libmobility::Mobility {
     psepar.Lx = i_par.Lx;
     psepar.Ly = i_par.Ly;
     psepar.Lz = i_par.Lz;
-    psepar.shearStrain = i_par.shearStrain;
+    psepar.shearStrain = i_par.shearStrain ? i_par.shearStrain.value() : 0.0;
   }
 
   void setPositions(device_span<const real> ipositions) override {
diff --git a/solvers/PSE/python_wrapper.cu b/solvers/PSE/python_wrapper.cu
index 7922373..0bc0342 100644
--- a/solvers/PSE/python_wrapper.cu
+++ b/solvers/PSE/python_wrapper.cu
@@ -31,12 +31,12 @@ This module will only accept periodic boundary conditions in the three direction
 )pbdoc";
 
 MOBILITY_PYTHONIFY_WITH_EXTRA_CODE(
-    PSE,
-    solver.def(
-        "setParameters",
-        [](PSE &self, real psi, real Lx, real Ly, real Lz, real shearStrain) {
-          self.setParametersPSE({psi, Lx, Ly, Lz, shearStrain});
-        },
-        docstringSetParameters, "psi"_a, "Lx"_a, "Ly"_a, "Lz"_a,
-        "shearStrain"_a);
+    PSE, solver.def(
+             "setParameters",
+             [](PSE &self, real psi, real Lx, real Ly, real Lz,
+                std::optional<real> shearStrain) {
+               self.setParametersPSE({psi, Lx, Ly, Lz, shearStrain});
+             },
+             docstringSetParameters, "psi"_a, "Lx"_a, "Ly"_a, "Lz"_a,
+             "shearStrain"_a = std::nullopt);
     , docstring);
diff --git a/tests/test_initialization.py b/tests/test_initialization.py
index 93a7b12..d82b77e 100644
--- a/tests/test_initialization.py
+++ b/tests/test_initialization.py
@@ -62,6 +62,24 @@ def test_nbody_default_parameters():
     solver.setPositions(positions)
 
 
+def test_pse_no_shear():
+    solver = PSE("periodic", "periodic", "periodic")
+    solver.setParameters(psi=1.0, Lx=10.0, Ly=10.0, Lz=10.0)
+    solver.initialize(hydrodynamicRadius=1.0, viscosity=1.0)
+
+
+# NBody should use default alg and all particles in one batch if no params set
+def test_nbody_no_params():
+    solver = NBody("open", "open", "open")
+    solver.initialize(
+        viscosity=1.0,
+        hydrodynamicRadius=1.5,
+    )
+    positions = np.random.rand(10, 3)
+    solver.setPositions(positions)
+    mf, _ = solver.Mdot(positions)
+
+
 @pytest.mark.parametrize(
     ("NBatch", "NperBatch", "numberParticles"),
     [