diff --git a/src/torchio/transforms/transform.py b/src/torchio/transforms/transform.py
index 93b4f8f7..2375e7ce 100644
--- a/src/torchio/transforms/transform.py
+++ b/src/torchio/transforms/transform.py
@@ -331,7 +331,7 @@ def _parse_range(
                         f'If {name} is a single number, it must be of'
                         f' type {type_constraint}, not {nums_range}',
                     )
-            min_range = -nums_range if min_constraint is None else nums_range
+            min_range = -nums_range if min_constraint is None else min_constraint
             return (min_range, nums_range)
 
         try:
diff --git a/tests/transforms/test_transforms.py b/tests/transforms/test_transforms.py
index be99c185..07b6c346 100644
--- a/tests/transforms/test_transforms.py
+++ b/tests/transforms/test_transforms.py
@@ -253,6 +253,10 @@ def test_arguments_are_and_are_not_dict(self):
         with pytest.raises(ValueError):
             transform.arguments_are_dict()
 
+    def test_min_constraint(self):
+        transform = tio.RandomNoise()
+        assert transform._parse_range(3, 'name', min_constraint=0) == (0, 3)
+
     def test_bad_over_max(self):
         transform = tio.RandomNoise()
         with pytest.raises(ValueError):