diff --git a/include/cantera/oneD/Inlet1D.h b/include/cantera/oneD/Inlet1D.h
index b31a31b18..6dd089992 100644
--- a/include/cantera/oneD/Inlet1D.h
+++ b/include/cantera/oneD/Inlet1D.h
@@ -65,7 +65,7 @@ public:
     }
 
     /// Set the mole fractions by specifying an array.
-    virtual void setMoleFractions(doublereal* xin) {
+    virtual void setMoleFractions(const doublereal* xin) {
         throw NotImplementedError("Bdry1D::setMoleFractions");
     }
 
@@ -157,7 +157,7 @@ public:
     }
 
     virtual void setMoleFractions(const std::string& xin);
-    virtual void setMoleFractions(doublereal* xin);
+    virtual void setMoleFractions(const doublereal* xin);
     virtual doublereal massFraction(size_t k) {
         return m_yin[k];
     }
@@ -279,7 +279,7 @@ public:
     }
 
     virtual void setMoleFractions(const std::string& xin);
-    virtual void setMoleFractions(doublereal* xin);
+    virtual void setMoleFractions(const doublereal* xin);
     virtual doublereal massFraction(size_t k) {
         return m_yres[k];
     }
diff --git a/src/oneD/boundaries1D.cpp b/src/oneD/boundaries1D.cpp
index c65558138..c97aee3f6 100644
--- a/src/oneD/boundaries1D.cpp
+++ b/src/oneD/boundaries1D.cpp
@@ -87,7 +87,7 @@ void Inlet1D::setMoleFractions(const std::string& xin)
     }
 }
 
-void Inlet1D::setMoleFractions(doublereal* xin)
+void Inlet1D::setMoleFractions(const doublereal* xin)
 {
     if (m_flow) {
         m_flow->phase().setMoleFractions(xin);
@@ -496,7 +496,7 @@ void OutletRes1D::setMoleFractions(const std::string& xres)
     }
 }
 
-void OutletRes1D::setMoleFractions(doublereal* xres)
+void OutletRes1D::setMoleFractions(const doublereal* xres)
 {
     if (m_flow) {
         m_flow->phase().setMoleFractions(xres);