diff --git a/include/nanobind/eigen/sparse.h b/include/nanobind/eigen/sparse.h
index 96442161..f253feb5 100644
--- a/include/nanobind/eigen/sparse.h
+++ b/include/nanobind/eigen/sparse.h
@@ -183,15 +183,12 @@ struct type_caster<Eigen::Map<T>, enable_if_t<is_eigen_sparse_matrix_v<T>>> {
         }
         if (object data_o = obj.attr("data"); !data_caster.from_python(data_o, flags, cleanup))
             return false;
-        ScalarNDArray& values = data_caster.value;
 
         if (object indices_o = obj.attr("indices"); !indices_caster.from_python(indices_o, flags, cleanup))
             return false;
-        StorageIndexNDArray& inner_indices = indices_caster.value;
 
         if (object indptr_o = obj.attr("indptr"); !indptr_caster.from_python(indptr_o, flags, cleanup))
             return false;
-        StorageIndexNDArray& outer_indices = indptr_caster.value;
 
         object shape_o = obj.attr("shape"), nnz_o = obj.attr("nnz");
         try {
diff --git a/tests/test_eigen.cpp b/tests/test_eigen.cpp
index 8e555546..a3e32660 100644
--- a/tests/test_eigen.cpp
+++ b/tests/test_eigen.cpp
@@ -2,6 +2,7 @@
 #include <nanobind/eigen/dense.h>
 #include <nanobind/eigen/sparse.h>
 #include <nanobind/trampoline.h>
+#include <iostream>
 
 namespace nb = nanobind;
 
@@ -166,8 +167,16 @@ NB_MODULE(test_eigen_ext, m) {
         assert(!m.isCompressed());
         return m.markAsRValue();
     });
+    // This function doesn't appear to be called in tests/test_eigen.py
     m.def("sparse_complex", []() -> Eigen::SparseMatrix<std::complex<double>> { return {}; });
 
+    m.def("sparse_map_c", [](const Eigen::Map<const SparseMatrixC> &) { });
+    m.def("sparse_map_r", [](const Eigen::Map<const SparseMatrixR> &) { });
+    m.def("sparse_update_map_to_zero_c", [](nb::object obj) {
+        Eigen::Map<SparseMatrixC> c = nb::cast<Eigen::Map<SparseMatrixC>>(obj);
+        for (int i = 0; i < c.nonZeros(); ++i) { c.valuePtr()[i] = 0; }
+    });
+
     /// issue #166
     using Matrix1d = Eigen::Matrix<double,1,1>;
     try {
diff --git a/tests/test_eigen.py b/tests/test_eigen.py
index 4e402ee3..0f15e576 100644
--- a/tests/test_eigen.py
+++ b/tests/test_eigen.py
@@ -374,3 +374,25 @@ def test14_single_element():
     a = np.array([[1]], dtype=np.uint32)
     assert a.ndim == 2 and a.shape == (1, 1)
     t.addMXuCC(a, a)
+
+@needs_numpy_and_eigen
+def test15_sparse_map():
+    pytest.importorskip("scipy")
+    import scipy
+    c = scipy.sparse.csc_matrix([[1, 0], [0, 1]], dtype=float)
+    # These should be copy-less
+    t.sparse_map_c(c)
+    r = scipy.sparse.csr_matrix([[1, 0], [0, 1]], dtype=float)
+    t.sparse_map_r(r)
+    # These should be ok, but will copy(?)
+    t.sparse_map_c(r)
+    t.sparse_map_r(c)
+
+    t.sparse_update_map_to_zero_c(c);
+    # check that c.sum() is zero now
+    assert c.sum() == 0
+    
+
+
+
+