diff --git a/pgvector/sparsevec.py b/pgvector/sparsevec.py
index 3631f78..be431dd 100644
--- a/pgvector/sparsevec.py
+++ b/pgvector/sparsevec.py
@@ -115,10 +115,15 @@ def _from_sparse(self, arr: sparray | spmatrix, /) -> None:
 
         if hasattr(value, 'coords'):
             # scipy 1.13+
-            self._indices = value.coords[-1].tolist()
+            indices = value.coords[-1].tolist()
         else:
-            self._indices = value.col.tolist()
-        self._values = [float(v) for v in value.data]
+            indices = value.col.tolist()
+
+        # coordinates are not necessarily ordered, and sparsevec requires ascending indices
+        elements = sorted(zip(indices, value.data))
+
+        self._indices = [int(v[0]) for v in elements]
+        self._values = [float(v[1]) for v in elements]
 
     def _from_dense(self, value: list[float] | ndarray, /) -> None:
         self._dim = len(value)
diff --git a/tests/test_sparse_vector.py b/tests/test_sparse_vector.py
index 1924f98..59a943a 100644
--- a/tests/test_sparse_vector.py
+++ b/tests/test_sparse_vector.py
@@ -60,6 +60,17 @@ def test_coo_array(self) -> None:
         assert vec.indices() == [0, 2, 4]
         assert isinstance(vec.values()[0], float)
 
+    def test_coo_array_unordered(self) -> None:
+        if np is None or sparse is None:
+            pytest.skip('NumPy and SciPy required')
+
+        arr = sparse.coo_array(([3, 1, 2], ([4, 0, 2],)), shape=(6,))
+        vec = SparseVector(arr)
+        assert vec.indices() == [0, 2, 4]
+        assert vec.values() == [1, 2, 3]
+        assert vec.to_text() == '{1:1.0,3:2.0,5:3.0}/6'
+        assert vec.to_binary() == pack('>iii3i3f', 6, 3, 0, 0, 2, 4, 1, 2, 3)
+
     def test_coo_array_dimensions(self) -> None:
         if np is None or sparse is None:
             pytest.skip('NumPy and SciPy required')