diff --git a/opm/simulators/linalg/bda/opencl/openclBILU0.hpp b/opm/simulators/linalg/bda/opencl/openclBILU0.hpp
index be46ca261..f52badbad 100644
--- a/opm/simulators/linalg/bda/opencl/openclBILU0.hpp
+++ b/opm/simulators/linalg/bda/opencl/openclBILU0.hpp
@@ -103,7 +103,7 @@ public:
     // via Lz = y
     // and Ux = z
     void apply(const cl::Buffer& y, cl::Buffer& x) override;
-    void apply(Scalar& y, Scalar& x) {}
+    void apply(Scalar&, Scalar&) {}
 
     std::tuple<std::vector<int>, std::vector<int>, std::vector<int>>
     get_preconditioner_structure()
diff --git a/opm/simulators/linalg/bda/opencl/openclBISAI.hpp b/opm/simulators/linalg/bda/opencl/openclBISAI.hpp
index 3ae14000a..5bb524f40 100644
--- a/opm/simulators/linalg/bda/opencl/openclBISAI.hpp
+++ b/opm/simulators/linalg/bda/opencl/openclBISAI.hpp
@@ -125,7 +125,7 @@ public:
 
     // apply preconditioner, x = prec(y)
     void apply(const cl::Buffer& y, cl::Buffer& x) override;
-    void apply(Scalar& y, Scalar& x) {}
+    void apply(Scalar&, Scalar&) {}
 };
 
 /// Similar function to csrPatternToCsc. It gives an offset map from CSR to CSC instead of the full CSR to CSC conversion.
diff --git a/opm/simulators/linalg/bda/opencl/openclCPR.hpp b/opm/simulators/linalg/bda/opencl/openclCPR.hpp
index a80d2b313..bf5a75a13 100644
--- a/opm/simulators/linalg/bda/opencl/openclCPR.hpp
+++ b/opm/simulators/linalg/bda/opencl/openclCPR.hpp
@@ -95,7 +95,7 @@ public:
     // applies blocked ilu0
     // also applies amg for pressure component
     void apply(const cl::Buffer& y, cl::Buffer& x) override;
-    void apply(Scalar& y, Scalar& x) {}
+    void apply(Scalar&, Scalar&) {}
 
     bool create_preconditioner(BlockedMatrix<Scalar>* mat) override;
     bool create_preconditioner(BlockedMatrix<Scalar>* mat,