diff --git a/test/freeflow/navierstokesnc/msfreeflowtestproblem.hh b/test/freeflow/navierstokesnc/msfreeflowtestproblem.hh
index d249d46c30bc23f68580d344d51683cfe291c90e..4195349bbd190ec1e6b491490566018dcf5c0ade 100644
--- a/test/freeflow/navierstokesnc/msfreeflowtestproblem.hh
+++ b/test/freeflow/navierstokesnc/msfreeflowtestproblem.hh
@@ -118,8 +118,8 @@ public:
     template <class FluidState>
     static Scalar binaryDiffusionCoefficient(const FluidState &fluidState,
                                              int phaseIdx,
-                                             unsigned int compIIdx,
-                                             unsigned int compJIdx)
+                                             int compIIdx,
+                                             int compJIdx)
     {
         if (compIIdx > compJIdx)
         {