diff --git a/interfaces/cython/cantera/test/test_reactor.py b/interfaces/cython/cantera/test/test_reactor.py
index 638dbddef22..7669554cfee 100644
--- a/interfaces/cython/cantera/test/test_reactor.py
+++ b/interfaces/cython/cantera/test/test_reactor.py
@@ -1048,9 +1048,9 @@ class TestSurfaceKinetics(utilities.CanteraTest):
     def make_reactors(self):
         self.net = ct.ReactorNet()
 
-        self.gas = ct.Solution('diamond.xml', 'gas')
-        self.solid = ct.Solution('diamond.xml', 'diamond')
-        self.interface = ct.Interface('diamond.xml', 'diamond_100',
+        self.gas = ct.Solution('diamond.yaml', 'gas')
+        self.solid = ct.Solution('diamond.yaml', 'diamond')
+        self.interface = ct.Interface('diamond.yaml', 'diamond_100',
                                       (self.gas, self.solid))
         self.gas.TPX = None, 1.0e3, 'H:0.002, H2:1, CH4:0.01, CH3:0.0002'
         self.r1 = ct.IdealGasReactor(self.gas)
diff --git a/src/zeroD/Reactor.cpp b/src/zeroD/Reactor.cpp
index da3f985312b..61c64988bfb 100644
--- a/src/zeroD/Reactor.cpp
+++ b/src/zeroD/Reactor.cpp
@@ -94,10 +94,6 @@ void Reactor::initialize(doublereal t0)
         m_nv += S->thermo()->nSpecies();
         size_t nt = S->kinetics()->nTotalSpecies();
         maxnt = std::max(maxnt, nt);
-        if (m_chem && &m_kin->thermo(0) != &S->kinetics()->thermo(0)) {
-            throw CanteraError("Reactor::initialize",
-                "First phase of all kinetics managers must be the gas.");
-        }
     }
     m_work.resize(maxnt);
 }