diff --git a/include/cantera/transport/LiquidTransport.h b/include/cantera/transport/LiquidTransport.h
index 935b04b8d..6c00ed41f 100644
--- a/include/cantera/transport/LiquidTransport.h
+++ b/include/cantera/transport/LiquidTransport.h
@@ -636,9 +636,9 @@ public:
      */
     virtual void getSpeciesFluxesES(size_t ndim,
                                     const doublereal* grad_T,
-                                    int ldx,
+                                    size_t ldx,
                                     const doublereal* grad_X,
-                                    int ldf,
+                                    size_t ldf,
                                     const doublereal* grad_Phi,
                                     doublereal* fluxes);
 
diff --git a/src/transport/LiquidTransport.cpp b/src/transport/LiquidTransport.cpp
index a2ee99d3d..00138403b 100644
--- a/src/transport/LiquidTransport.cpp
+++ b/src/transport/LiquidTransport.cpp
@@ -1143,9 +1143,9 @@ void LiquidTransport::getSpeciesFluxes(size_t ndim,
  */
 void LiquidTransport::getSpeciesFluxesES(size_t ndim,
         const doublereal* grad_T,
-        int ldx,
+        size_t ldx,
         const doublereal* grad_X,
-        int ldf,
+        size_t ldf,
         const doublereal* grad_V,
         doublereal* fluxes)
 {