diff --git a/include/bh_python/register_histogram.hpp b/include/bh_python/register_histogram.hpp
index bf488ae24..eb36bc01f 100644
--- a/include/bh_python/register_histogram.hpp
+++ b/include/bh_python/register_histogram.hpp
@@ -190,16 +190,17 @@ auto register_histogram(py::module& m, const char* name, const char* desc) {
 
         .def("reduce",
              [](const histogram_t& self, py::args args) {
+                 auto commands
+                     = py::cast<std::vector<bh::algorithm::reduce_command>>(args);
                  py::gil_scoped_release release;
-                 return bh::algorithm::reduce(
-                     self, py::cast<std::vector<bh::algorithm::reduce_command>>(args));
+                 return bh::algorithm::reduce(self, commands);
              })
 
         .def("project",
              [](const histogram_t& self, py::args values) {
+                 auto cpp_values = py::cast<std::vector<unsigned>>(values);
                  py::gil_scoped_release release;
-                 return bh::algorithm::project(self,
-                                               py::cast<std::vector<unsigned>>(values));
+                 return bh::algorithm::project(self, cpp_values);
              })
 
         .def("fill", &fill<histogram_t>)
diff --git a/src/boost_histogram/_internal/hist.py b/src/boost_histogram/_internal/hist.py
index ba8d0d5eb..ab5e6fb0b 100644
--- a/src/boost_histogram/_internal/hist.py
+++ b/src/boost_histogram/_internal/hist.py
@@ -998,6 +998,11 @@ def project(self: H, *args: int) -> Union[H, float, Accumulator]:
         Provided a list of axis numbers, this will produce the histogram over
         those axes only. Flow bins are used if available.
         """
+        for arg in args:
+            if arg < 0 or arg >= self.ndim:
+                raise ValueError(
+                    f"Projection axis must be a valid axis number 0 to {self.ndim-1}, not {arg}"
+                )
 
         return self._new_hist(self._hist.project(*args))
 
diff --git a/tests/test_histogram.py b/tests/test_histogram.py
index 9ccf8f8b9..dfd52dfae 100644
--- a/tests/test_histogram.py
+++ b/tests/test_histogram.py
@@ -590,6 +590,12 @@ def test_project():
     with pytest.raises(ValueError):
         h.project(2, 1)
 
+    with pytest.raises(ValueError):
+        h.project(9)
+
+    with pytest.raises(ValueError):
+        h.project(-1)
+
 
 def test_shrink_1d():
     h = bh.Histogram(bh.axis.Regular(20, 1, 5))