diff --git a/pgvector/sparsevec.py b/pgvector/sparsevec.py
index 0d3434c..a76cea2 100644
--- a/pgvector/sparsevec.py
+++ b/pgvector/sparsevec.py
@@ -100,6 +100,8 @@ def _from_dict(self, d: dict[int, float], dim: int) -> None:
 
         self._dim = int(dim)
         self._indices = [int(v[0]) for v in elements]
+        if any(i < 0 or i >= self._dim for i in self._indices):
+            raise ValueError('sparsevec index out of bounds')
         self._values = [float(v[1]) for v in elements]
 
     def _from_sparse(self, arr: sparray | spmatrix, /) -> None:
diff --git a/tests/test_sparse_vector.py b/tests/test_sparse_vector.py
index 262e23a..986d87c 100644
--- a/tests/test_sparse_vector.py
+++ b/tests/test_sparse_vector.py
@@ -45,6 +45,11 @@ def test_dict(self) -> None:
     def test_dict_empty(self) -> None:
         assert SparseVector({}, 0).to_list() == []
 
+    @pytest.mark.parametrize('index', [-1, 3])
+    def test_dict_index_out_of_bounds(self, index: int) -> None:
+        with pytest.raises(ValueError, match='sparsevec index out of bounds'):
+            SparseVector({index: 1}, 3)
+
     def test_dict_no_dimensions(self) -> None:
         with pytest.raises(ValueError) as error:
             SparseVector({0: 1, 2: 2, 4: 3})  # type: ignore