diff --git a/include/cantera/zeroD/ReactorNet.h b/include/cantera/zeroD/ReactorNet.h
index 884b51839..d0f9bd554 100644
--- a/include/cantera/zeroD/ReactorNet.h
+++ b/include/cantera/zeroD/ReactorNet.h
@@ -249,7 +249,10 @@ protected:
     vector_fp m_atol;
     doublereal m_rtol, m_rtolsens;
     doublereal m_atols, m_atolsens;
+
+    //! Maximum integrator internal timestep. Default of 0.0 means infinity.
     doublereal m_maxstep;
+
     int m_maxErrTestFails;
     bool m_verbose;
     size_t m_ntotpar;
diff --git a/interfaces/cython/cantera/test/test_reactor.py b/interfaces/cython/cantera/test/test_reactor.py
index ab1ba960a..c5ceb19da 100644
--- a/interfaces/cython/cantera/test/test_reactor.py
+++ b/interfaces/cython/cantera/test/test_reactor.py
@@ -378,6 +378,7 @@ class TestReactor(utilities.CanteraTest):
         # (constant T) we can compare with an analytical solution for
         # the mass of each reactor as a function of time
         self.make_reactors(P1=10*ct.one_atm)
+        self.net.rtol = 1e-11
         self.r1.energy_enabled = False
         self.r2.energy_enabled = False
         valve = ct.Valve(self.r1, self.r2)
diff --git a/src/zeroD/ReactorNet.cpp b/src/zeroD/ReactorNet.cpp
index 52e201c58..a412aca02 100644
--- a/src/zeroD/ReactorNet.cpp
+++ b/src/zeroD/ReactorNet.cpp
@@ -14,7 +14,7 @@ ReactorNet::ReactorNet() :
     m_integ(0), m_time(0.0), m_init(false), m_integrator_init(false),
     m_nv(0), m_rtol(1.0e-9), m_rtolsens(1.0e-4),
     m_atols(1.0e-15), m_atolsens(1.0e-4),
-    m_maxstep(-1.0), m_maxErrTestFails(0),
+    m_maxstep(0.0), m_maxErrTestFails(0),
     m_verbose(false), m_ntotpar(0)
 {
     m_integ = newIntegrator("CVODE");
@@ -113,9 +113,6 @@ void ReactorNet::reinitialize()
 void ReactorNet::advance(doublereal time)
 {
     if (!m_init) {
-        if (m_maxstep < 0.0) {
-            m_maxstep = time - m_time;
-        }
         initialize();
     } else if (!m_integrator_init) {
         reinitialize();
@@ -128,9 +125,6 @@ void ReactorNet::advance(doublereal time)
 double ReactorNet::step(doublereal time)
 {
     if (!m_init) {
-        if (m_maxstep < 0.0) {
-            m_maxstep = time - m_time;
-        }
         initialize();
     } else if (!m_integrator_init) {
         reinitialize();