diff --git a/CMakeLists.txt b/CMakeLists.txt
index c82883cd93..79c4f315d2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -750,6 +750,11 @@ endif()
 
 add_custom_target(extra_test ${CMAKE_CTEST_COMMAND} -C ExtraTests)
 
+# must activate avx2 flags for mixed precision.
+if(HAVE_AVX2_EXTENSION)
+  set_property(SOURCE ${AVX2_SOURCE_FILES} PROPERTY COMPILE_FLAGS ${AVX2_FLAGS})
+endif()
+
 # must link libraries after target 'opmsimulators' has been defined
 
 if(CUDA_FOUND)
diff --git a/CMakeLists_files.cmake b/CMakeLists_files.cmake
index 02cd6aafd7..a387fe41d5 100644
--- a/CMakeLists_files.cmake
+++ b/CMakeLists_files.cmake
@@ -166,9 +166,6 @@ list (APPEND MAIN_SOURCE_FILES
   opm/simulators/linalg/FlexibleSolver5.cpp
   opm/simulators/linalg/FlexibleSolver6.cpp
   opm/simulators/linalg/FlowLinearSolverParameters.cpp
-  opm/simulators/linalg/mixed/bsr.c
-  opm/simulators/linalg/mixed/prec.c
-  opm/simulators/linalg/mixed/bslv.c
   opm/simulators/linalg/ISTLSolver.cpp
   opm/simulators/linalg/MILU.cpp
   opm/simulators/linalg/ParallelIstlInformation.cpp
@@ -265,6 +262,15 @@ list (APPEND MAIN_SOURCE_FILES
   opm/simulators/wells/WGState.cpp
   )
 
+if (HAVE_AVX2_EXTENSION)
+  set (AVX2_SOURCE_FILES
+    opm/simulators/linalg/mixed/bsr.c
+    opm/simulators/linalg/mixed/prec.c
+    opm/simulators/linalg/mixed/bslv.c)
+  list (APPEND MAIN_SOURCE_FILES
+    ${AVX2_SOURCE_FILES})
+endif()
+
 if (HAVE_ECL_INPUT)
   list (APPEND MAIN_SOURCE_FILES
     opm/simulators/utils/satfunc/GasPhaseConsistencyChecks.cpp
diff --git a/opm-simulators-prereqs.cmake b/opm-simulators-prereqs.cmake
index 58bb27ec9e..2488460b02 100644
--- a/opm-simulators-prereqs.cmake
+++ b/opm-simulators-prereqs.cmake
@@ -6,6 +6,7 @@ set (opm-simulators_CONFIG_VAR
   HAVE_MPI
   HAVE_PETSC
   COMPILE_GPU_BRIDGE
+  HAVE_AVX2_EXTENSION
   HAVE_CUDA
   HAVE_OPENCL
   HAVE_OPENCL_HPP
@@ -37,6 +38,10 @@ if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.30.0)
 	set(_Boost_CONFIG_MODE CONFIG)
 endif()
 
+# Enable when available
+#include(CheckAVX2)
+#check_for_avx2()
+
 # dependencies
 set (opm-simulators_DEPS
   # Compile with C99 support if available
diff --git a/opm/simulators/linalg/FlexibleSolver_impl.hpp b/opm/simulators/linalg/FlexibleSolver_impl.hpp
index 12c228fb50..b67fc0b12f 100644
--- a/opm/simulators/linalg/FlexibleSolver_impl.hpp
+++ b/opm/simulators/linalg/FlexibleSolver_impl.hpp
@@ -32,7 +32,9 @@
 #include <opm/simulators/linalg/PreconditionerFactoryGPUIncludeWrapper.hpp>
 #include <opm/simulators/linalg/is_gpu_operator.hpp>
 
+#if HAVE_AVX2_EXTENSION
 #include <opm/simulators/linalg/mixed/wrapper.hpp>
+#endif
 
 #include <dune/common/fmatrix.hh>
 #include <dune/istl/bcrsmatrix.hh>
@@ -183,8 +185,9 @@ namespace Dune
                                                                             tol, // desired residual reduction factor
                                                                             maxiter, // maximum number of iterations
                                                                             verbosity);
-        } else if (solver_type == "mixed-bicgstab") {
-            if constexpr (!Opm::is_gpu_operator_v<Operator>) {
+#if HAVE_AVX2_EXTENSION
+          } else if (solver_type == "mixed-bicgstab") {
+              if constexpr (!Opm::is_gpu_operator_v<Operator>) {
                 const std::string prec_type = prm.get<std::string>("preconditioner.type", "error");
                 bool use_mixed_dilu= (prec_type=="mixed-dilu");
                 using MatrixType = decltype(linearoperator_for_solver_->getmat());
@@ -197,6 +200,7 @@ namespace Dune
             } else {
                 OPM_THROW(std::invalid_argument, "mixed-bicgstab solver not supported for GPU operators.");
             }
+#endif
         } else if (solver_type == "loopsolver") {
             linsolver_ = std::make_shared<Dune::LoopSolver<VectorType>>(*linearoperator_for_solver_,
                                                                         *scalarproduct_,