diff --git a/opm/simulators/linalg/bda/CPR.cpp b/opm/simulators/linalg/bda/CPR.cpp
index cd18855ba..4da4d69ce 100644
--- a/opm/simulators/linalg/bda/CPR.cpp
+++ b/opm/simulators/linalg/bda/CPR.cpp
@@ -140,7 +140,8 @@ void CPR<block_size>::create_preconditioner(BlockedMatrix *mat_) {
             }
         }
 
-        // transform blocks to scalars
+        // extract pressure
+        // transform blocks to scalars to create scalar linear system
         for (int row = 0; row < Nb; ++row) {
             int start = mat->rowPointers[row];
             int end = mat->rowPointers[row + 1];
diff --git a/opm/simulators/linalg/bda/openclKernels.cpp b/opm/simulators/linalg/bda/openclKernels.cpp
index 74b3ef883..836ee5a1e 100644
--- a/opm/simulators/linalg/bda/openclKernels.cpp
+++ b/opm/simulators/linalg/bda/openclKernels.cpp
@@ -507,7 +507,8 @@ void OpenclKernels::apply_stdwells_no_reorder(cl::Buffer& d_Cnnzs_ocl, cl::Buffe
         )";
     }
 
-    // multiply vector with another vector, element-wise
+    // multiply vector with another vector and a scalar, element-wise
+    // add result to a third vector
     std::string OpenclKernels::get_vmul_source() {
         return R"(
         __kernel void vmul(