diff --git a/interfaces/cython/cantera/onedim.pyx b/interfaces/cython/cantera/onedim.pyx
index 764f33c1a..0358de3b2 100644
--- a/interfaces/cython/cantera/onedim.pyx
+++ b/interfaces/cython/cantera/onedim.pyx
@@ -208,12 +208,9 @@ cdef class Boundary1D(Domain1D):
             return self.phase.X
 
         def __set__(self, X):
-            cdef np.ndarray[np.double_t, ndim=1] data
-            if isinstance(X, (str, unicode)):
-                self.boundary.setMoleFractions(stringify(X))
-            else:
-                data = np.ascontiguousarray(X, dtype=np.double)
-                self.boundary.setMoleFractions(&data[0])
+            self.phase.TPX = None, None, X
+            cdef np.ndarray[np.double_t, ndim=1] data = self.phase.X
+            self.boundary.setMoleFractions(&data[0])
 
     property Y:
         """
diff --git a/interfaces/cython/cantera/test/test_onedim.py b/interfaces/cython/cantera/test/test_onedim.py
index e3febd7e8..38b479daa 100644
--- a/interfaces/cython/cantera/test/test_onedim.py
+++ b/interfaces/cython/cantera/test/test_onedim.py
@@ -47,6 +47,9 @@ class TestOnedim(utilities.CanteraTest):
         self.assertArrayNear(inlet.X, Xref)
         self.assertArrayNear(inlet.Y, Yref)
 
+        inlet.X = {'H2':0.3, 'O2':0.5, 'AR':0.2}
+        self.assertNear(inlet.X[gas2.species_index('H2')], 0.3)
+
     def test_unpicklable(self):
         import pickle
         gas = ct.Solution('h2o2.xml')