diff --git a/pyproximal/proximal/Box.py b/pyproximal/proximal/Box.py
index 9f52cf3..7adc82d 100644
--- a/pyproximal/proximal/Box.py
+++ b/pyproximal/proximal/Box.py
@@ -38,7 +38,7 @@ def __init__(
         self.box = BoxProj(self.lower, self.upper)
 
     def __call__(self, x: NDArray) -> bool:
-        return bool(np.all((x > self.lower) & (x < self.upper)))
+        return bool(np.all((x >= self.lower) & (x <= self.upper)))
 
     @_check_tau
     def prox(self, x: NDArray, tau: float) -> NDArray:
diff --git a/pytests/test_projection.py b/pytests/test_projection.py
index 2b91cca..b2d66e4 100644
--- a/pytests/test_projection.py
+++ b/pytests/test_projection.py
@@ -31,6 +31,11 @@ def test_Box(par):
     box = Box(-1, 1)
     x = np.random.normal(0.0, 1.0, par["nx"]).astype(par["dtype"])
 
+    # evaluation
+    assert box(x) is False
+    xp = box.prox(x, 1.0)
+    assert box(xp) is True
+
     # prox / dualprox
     tau = 2.0
     assert moreau(box, x, tau)