diff --git a/src/oneD/IonFlow.cpp b/src/oneD/IonFlow.cpp
index 267a2e9db..d21988717 100644
--- a/src/oneD/IonFlow.cpp
+++ b/src/oneD/IonFlow.cpp
@@ -45,6 +45,10 @@ IonFlow::IonFlow(IdealGasPhase* ph, size_t nsp, size_t points) :
     // no bound for electric potential
     setBounds(c_offset_P, -1.0e20, 1.0e20);
 
+    // Set tighter negative species limit on electron concentration to avoid
+    // instabilities
+    setBounds(c_offset_Y + m_kElectron, -1e-16, 1.0);
+
     m_refiner->setActive(c_offset_P, false);
     m_mobility.resize(m_nsp*m_points);
     m_do_poisson.resize(m_points,false);