diff --git a/src/petsc4Foam/solvers/petscSolver.C b/src/petsc4Foam/solvers/petscSolver.C
index 0c0e09b608b7e1cceb8a0da58215b9e28d9c9320..e0803841658d18a31975849073cd32e5ca1ec77e 100644
--- a/src/petsc4Foam/solvers/petscSolver.C
+++ b/src/petsc4Foam/solvers/petscSolver.C
@@ -99,7 +99,7 @@ Foam::petscSolver::petscSolver
     ),
     petscDict_(solverControls.subDict("petsc")),
     eqName_(fieldName),
-    prefix_("sub_" + eqName_ + "_")
+    prefix_("eqn_" + eqName_ + "_")
 {}
 
 
@@ -305,7 +305,7 @@ void Foam::petscSolver::buildKsp
     // Create parallel solver context
     KSPCreate(PETSC_COMM_WORLD, &ksp);
 
-    // Set the prefix for the options db (e.g. -sub_p_)
+    // Set the prefix for the options db (e.g. -eqn_p_)
     KSPSetOptionsPrefix(ksp, prefix_.c_str());
 
     // ksp set operator and preconditioner
@@ -408,7 +408,7 @@ void Foam::petscSolver::computeMatAllocation
     MatCreate(PETSC_COMM_WORLD, &Amat);
     MatSetSizes(Amat, nrows_, nrows_, PETSC_DECIDE, PETSC_DECIDE);
 
-    // Set the prefix for the options db (e.g. -sub_p_)
+    // Set the prefix for the options db (e.g. -eqn_p_)
     MatSetOptionsPrefix(Amat, prefix_.c_str());
     dictionary matDict  = petscDict_.subOrEmptyDict("matCoeffs");
     PetscUtils::setFlags(prefix_ + "mat_", matDict);