diff --git a/src/python/histogram.cpp b/src/python/histogram.cpp
index d6a09ef1..72d527c0 100644
--- a/src/python/histogram.cpp
+++ b/src/python/histogram.cpp
@@ -56,8 +56,13 @@ histogram_fill(python::tuple args, python::dict kwargs) {
     histogram& self = extract<histogram&>(args[0]);
 
     object ow;
-    if (kwargs)
-        ow = kwargs["w"];
+    if (kwargs) {
+        if (len(kwargs) > 1 || !kwargs.has_key("w")) {
+            PyErr_SetString(PyExc_RuntimeError, "only keyword w allowed");
+            throw_error_already_set();
+        }
+        ow = kwargs.get("w");
+    }
 
 #ifdef HAVE_NUMPY
     if (nargs == 2) {
@@ -90,7 +95,6 @@ histogram_fill(python::tuple args, python::dict kwargs) {
                     throw_error_already_set();
             }
 
-            PyArrayObject* aw = 0;
             if (!ow.is_none()) {
                 if (PySequence_Check(ow.ptr())) {
                     PyArrayObject* aw = (PyArrayObject*)
@@ -109,16 +113,18 @@ histogram_fill(python::tuple args, python::dict kwargs) {
                         PyErr_SetString(PyExc_ValueError, "sizes do not match");
                         throw_error_already_set();
                     }
-                }
-            }            
 
-            if (aw) {
-                for (unsigned i = 0; i < dims[0]; ++i) {
-                    double* v = (double*)PyArray_GETPTR1(a, i);
-                    double* w = (double*)PyArray_GETPTR1(aw, i);
-                    self.wfill_c(self.dim(), v, *w);
+                    for (unsigned i = 0; i < dims[0]; ++i) {
+                        double* v = (double*)PyArray_GETPTR1(a, i);
+                        double* w = (double*)PyArray_GETPTR1(aw, i);
+                        self.wfill_c(self.dim(), v, *w);
+                    }
+
+                    Py_DECREF(aw);
+                } else {
+                    PyErr_SetString(PyExc_ValueError, "w is not a sequence");
+                    throw_error_already_set();
                 }
-                Py_DECREF(aw);
             } else {
                 for (unsigned i = 0; i < dims[0]; ++i) {
                     double* v = (double*)PyArray_GETPTR1(a, i);
diff --git a/test/python_suite_test.py.in b/test/python_suite_test.py.in
index e9e89fe2..2d314d74 100755
--- a/test/python_suite_test.py.in
+++ b/test/python_suite_test.py.in
@@ -577,13 +577,59 @@ class histogram_test(unittest.TestCase):
     def test_fill_with_numpy_array_0(self):
         a = histogram(integer_axis(0, 2, uoflow=False))
         a.fill(numpy.array([-1, 0, 1, 2, 1, 4]))
-        self.assertEqual(a.value(0), 1)
-        self.assertEqual(a.value(1), 2)
-        self.assertEqual(a.value(2), 1)
+        a.fill((-1, 0))
+        a.fill([1, 2])
+        self.assertEqual(a.value(0), 2)
+        self.assertEqual(a.value(1), 3)
+        self.assertEqual(a.value(2), 2)
+
         with self.assertRaises(ValueError):
             a.fill(numpy.empty((2, 2)))
+        with self.assertRaises(ValueError):
+            a.fill(numpy.empty((1, 2, 2)))
         with self.assertRaises(RuntimeError):
             a.fill(numpy.empty((2, 1)), 1)
+        with self.assertRaises(ValueError):
+            a.fill("abc")
+
+        a = histogram(integer_axis(0, 1, uoflow=False),
+                      regular_axis(2, 0, 2, uoflow=False))
+        a.fill(numpy.array([[-1., -1.], [0., 1.], [1., 0.1]]))
+        self.assertEqual(a.value(0, 0), 0)
+        self.assertEqual(a.value(0, 1), 1)
+        self.assertEqual(a.value(1, 0), 1)
+        self.assertEqual(a.value(1, 1), 0)
+
+        with self.assertRaises(ValueError):
+            a.fill((1, 2, 3))
+
+        a = histogram(integer_axis(0, 2, uoflow=False))
+        a.fill([0, 0, 1, 2])
+        a.fill((1, 0, 2, 2))
+        self.assertEqual(a.value(0), 3)
+        self.assertEqual(a.value(1), 2)
+        self.assertEqual(a.value(2), 3)
+
+
+    @unittest.skipUnless(have_numpy, "requires build with numpy-support")
+    def test_fill_with_numpy_array_1(self):
+        a = histogram(integer_axis(0, 2, uoflow=True))
+        v = numpy.array([-1, 0, 1, 2, 3, 4])
+        w = numpy.array([ 2, 3, 4, 5, 6, 7])
+        a.fill(v, w=w)
+        a.fill([0, 1], w=[2.0, 3.0])
+        self.assertEqual(a.value(0), 5)
+        self.assertEqual(a.value(1), 7)
+        self.assertEqual(a.value(2), 5)
+
+        with self.assertRaises(RuntimeError):
+            a.fill([1, 2], foo=1)
+        with self.assertRaises(ValueError):
+            a.fill([1, 2], w=1)
+        with self.assertRaises(RuntimeError):
+            a.fill([1, 2], w=[1], foo=1)
+        with self.assertRaises(ValueError):
+            a.fill([1, 2], w=[[1, 1], [2, 2]])
 
         a = histogram(integer_axis(0, 1, uoflow=False),
                       regular_axis(2, 0, 2, uoflow=False))
@@ -599,27 +645,5 @@ class histogram_test(unittest.TestCase):
         self.assertEqual(a.value(1), 2)
         self.assertEqual(a.value(2), 3)
 
-    @unittest.skipUnless(have_numpy, "requires build with numpy-support")
-    def test_fill_with_numpy_array_1(self):
-        a = histogram(integer_axis(0, 2, uoflow=False))
-        a.fill(numpy.array([-1, 0, 1, 2, 1, 4]),
-               w=numpy.array([2.0, 3.0, 4.0, 5.0, 6.0, 7.0]))
-        self.assertEqual(a.value(0), 1)
-        self.assertEqual(a.value(1), 2)
-        self.assertEqual(a.value(2), 1)
-        a = histogram(integer_axis(0, 1, uoflow=False),
-                       regular_axis(2, 0, 2, uoflow=False))
-        a.fill(numpy.array([[-1., -1.], [0., 1.], [1., 0.1]]))
-        self.assertEqual(a.value(0, 0), 0)
-        self.assertEqual(a.value(0, 1), 1)
-        self.assertEqual(a.value(1, 0), 1)
-        self.assertEqual(a.value(1, 1), 0)
-        a = histogram(integer_axis(0, 2, uoflow=False))
-        a.fill([0, 0, 1, 2])
-        a.fill((1, 0, 2, 2))
-        self.assertEqual(a.value(0), 3)
-        self.assertEqual(a.value(1), 2)
-        self.assertEqual(a.value(2), 3)
-
 if __name__ == "__main__":
     unittest.main()