diff --git a/pymatsolver/solvers.py b/pymatsolver/solvers.py
index 4d0317c..a1ab55b 100644
--- a/pymatsolver/solvers.py
+++ b/pymatsolver/solvers.py
@@ -77,8 +77,10 @@ def __init__(
         if is_symmetric is None:
             if sp.issparse(A):
                 is_symmetric = (A.T != A).nnz == 0
-            else:
+            elif isinstance(A, np.ndarray):
                 is_symmetric = issymmetric(A)
+            else:
+                is_symmetric = False
         self.is_symmetric = is_symmetric
         if is_hermitian is None:
             if self.is_real:
@@ -86,8 +88,10 @@ def __init__(
             else:
                 if sp.issparse(A):
                     is_hermitian = (A.T.conjugate() != A).nnz == 0
-                else:
+                elif isinstance(A, np.ndarray):
                     is_hermitian = ishermitian(A)
+                else:
+                    is_hermitian = False
 
         self.is_hermitian = is_hermitian
 
diff --git a/tests/test_Scipy.py b/tests/test_Scipy.py
index c07e0c9..a080031 100644
--- a/tests/test_Scipy.py
+++ b/tests/test_Scipy.py
@@ -1,5 +1,6 @@
 from pymatsolver import Solver, Diagonal, SolverCG, SolverLU
 import scipy.sparse as sp
+from scipy.sparse.linalg import aslinearoperator
 import numpy as np
 import numpy.testing as npt
 import pytest
@@ -57,6 +58,17 @@ def test_solver(a_matrix, n_rhs, solver):
 
     npt.assert_allclose(x, b, atol=tol)
 
+@pytest.mark.parametrize('dtype', [np.float64, np.complex128])
+def test_iterative_solver_linear_op(dtype):
+    n = 10
+    A = aslinearoperator(sp.eye(n).astype(dtype))
+
+    Ainv = SolverCG(A)
+
+    rhs = np.linspace(0.9, 1.1, n)
+
+    npt.assert_allclose(Ainv @ rhs, rhs)
+
 @pytest.mark.parametrize('n_rhs', [1, 5])
 def test_diag_solver(n_rhs):
     n = 10
diff --git a/tests/test_Wrappers.py b/tests/test_Wrappers.py
index 10b0dab..62a5809 100644
--- a/tests/test_Wrappers.py
+++ b/tests/test_Wrappers.py
@@ -14,12 +14,14 @@ def test_wrapper_unused_kwargs(solver_class):
     with pytest.warns(UnusedArgumentWarning, match="Unused keyword argument.*"):
         solver_class(A, not_a_keyword_arg=True)
 
+
 def test_good_arg_iterative():
     # Ensure this doesn't throw a warning!
     with warnings.catch_warnings():
         warnings.simplefilter("error")
         SolverCG(sp.eye(10), rtol=1e-4)
 
+
 def test_good_arg_direct():
     # Ensure this doesn't throw a warning!
     with warnings.catch_warnings():
@@ -40,7 +42,6 @@ def __init__(self, A):
         WrappedClass(sp.eye(2))
 
 
-
 def test_direct_clean_function():
     def direct_func(A):
         class Empty():
@@ -67,6 +68,7 @@ def clean(self):
     Ainv.clean()
     assert Ainv.solver.A is None
 
+
 def test_iterative_deprecations():
 
     with pytest.warns(FutureWarning, match="check_accuracy and accuracy_tol were unused.*"):
@@ -75,6 +77,7 @@ def test_iterative_deprecations():
     with pytest.warns(FutureWarning, match="check_accuracy and accuracy_tol were unused.*"):
         wrap_iterative(lambda a, x: x, accuracy_tol=1E-3)
 
+
 def test_non_scipy_iterative():
     def iterative_solver(A, x):
         return x