diff --git a/palace/linalg/mumps.hpp b/palace/linalg/mumps.hpp
index f84308939..57811b2c3 100644
--- a/palace/linalg/mumps.hpp
+++ b/palace/linalg/mumps.hpp
@@ -29,9 +29,9 @@ class MumpsSolver : public mfem::MUMPSSolver
            iodata.problem.type == ProblemType::ELECTROSTATIC ||
            iodata.problem.type == ProblemType::MAGNETOSTATIC)
               ? mfem::MUMPSSolver::SYMMETRIC_POSITIVE_DEFINITE
-          : iodata.solver.linear.complex_coarse_solve
-              ? mfem::MUMPSSolver::UNSYMMETRIC
-              : mfem::MUMPSSolver::SYMMETRIC_INDEFINITE,
+          : iodata.boundaries.periodic.wave_vector == std::array<double, 3>{0.0, 0.0, 0.0}
+              ? mfem::MUMPSSolver::SYMMETRIC_INDEFINITE
+              : mfem::MUMPSSolver::UNSYMMETRIC,
           iodata.solver.linear.sym_factorization,
           (iodata.solver.linear.strumpack_compression_type == SparseCompression::BLR)
               ? iodata.solver.linear.strumpack_lr_tol
diff --git a/palace/linalg/solver.cpp b/palace/linalg/solver.cpp
index 357b524a4..8c2539f75 100644
--- a/palace/linalg/solver.cpp
+++ b/palace/linalg/solver.cpp
@@ -55,8 +55,9 @@ void MfemWrapperSolver<ComplexOperator>::SetOperator(const ComplexOperator &op)
   {
     if (complex_matrix)
     {
-      // A = [Ar, -Ai]
-      //     [Ai,  Ar]
+      // A = [Ar, Ai]
+      //     [Ai, -Ar]
+      // We solve A [xr; -xi] = [br; bi]
       mfem::Array2D<const mfem::HypreParMatrix *> blocks(2, 2);
       mfem::Array2D<double> block_coeffs(2, 2);
       blocks(0, 0) = hAr;
@@ -64,9 +65,9 @@ void MfemWrapperSolver<ComplexOperator>::SetOperator(const ComplexOperator &op)
       blocks(1, 0) = hAi;
       blocks(1, 1) = hAr;
       block_coeffs(0, 0) = 1.0;
-      block_coeffs(0, 1) = -1.0;
+      block_coeffs(0, 1) = 1.0;
       block_coeffs(1, 0) = 1.0;
-      block_coeffs(1, 1) = 1.0;
+      block_coeffs(1, 1) = -1.0;
       A.reset(mfem::HypreParMatrixFromBlocks(blocks, &block_coeffs));
     }
     else
@@ -168,6 +169,8 @@ void MfemWrapperSolver<ComplexOperator>::Mult(const ComplexVector &x,
     Y.ReadWrite();
     yr.MakeRef(Y, 0, Ny);
     yi.MakeRef(Y, Ny, Ny);
+    // [yr; yi] is the complex conjugate of the solution
+    yi *= -1.0;
     y.Real() = yr;
     y.Imag() = yi;
   }