diff --git a/opm/models/blackoil/blackoilbrinemodules.hh b/opm/models/blackoil/blackoilbrinemodules.hh
index 18284aff5..12ab9b0af 100644
--- a/opm/models/blackoil/blackoilbrinemodules.hh
+++ b/opm/models/blackoil/blackoilbrinemodules.hh
@@ -163,14 +163,14 @@ public:
         priVars[saltConcentrationIdx] = fluidState.saltConcentration();
     }
 
-    static std::string primaryVarName(unsigned pvIdx)
+    static std::string primaryVarName([[maybe_unused]] unsigned pvIdx)
     {
         assert(primaryVarApplies(pvIdx));
 
         return "saltConcentration";
     }
 
-    static Scalar primaryVarWeight(unsigned pvIdx OPM_OPTIM_UNUSED)
+    static Scalar primaryVarWeight([[maybe_unused]] unsigned pvIdx)
     {
         assert(primaryVarApplies(pvIdx));
 
@@ -186,14 +186,14 @@ public:
         return eqIdx == contiBrineEqIdx;
     }
 
-    static std::string eqName(unsigned eqIdx)
+    static std::string eqName([[maybe_unused]] unsigned eqIdx)
     {
         assert(eqApplies(eqIdx));
 
         return "conti^brine";
     }
 
-    static Scalar eqWeight(unsigned eqIdx OPM_OPTIM_UNUSED)
+    static Scalar eqWeight([[maybe_unused]] unsigned eqIdx)
     {
         assert(eqApplies(eqIdx));
 
diff --git a/opm/models/blackoil/blackoilonephaseindices.hh b/opm/models/blackoil/blackoilonephaseindices.hh
index 58c2754a4..6e1233b05 100644
--- a/opm/models/blackoil/blackoilonephaseindices.hh
+++ b/opm/models/blackoil/blackoilonephaseindices.hh
@@ -122,12 +122,12 @@ struct BlackOilOnePhaseIndices
     //////////////////////
 
     //! \brief returns the index of "active" component
-    static unsigned canonicalToActiveComponentIndex(unsigned compIdx OPM_UNUSED)
+    static unsigned canonicalToActiveComponentIndex(unsigned /*compIdx*/)
     {
         return 0;
     }
 
-    static unsigned activeToCanonicalComponentIndex(unsigned compIdx)
+    static unsigned activeToCanonicalComponentIndex([[maybe_unused]] unsigned compIdx)
     {
         // assumes canonical oil = 0, water = 1, gas = 2;
         assert(compIdx == 0);