diff --git a/idefix/utils.py b/idefix/utils.py
index 701d0f8..0ac00c2 100644
--- a/idefix/utils.py
+++ b/idefix/utils.py
@@ -87,10 +87,10 @@ def fit_bbox(data, decimals=0):
     --------
     bbox : Returns a raw bounding box on the data.
     """
-    bbox = bbox(data)
+    raw_bbox = bbox(data)
 
-    nbbox = np.round(bbox, decimals)
-    nbbox[0,2] = np.floor(bbox * 10 ** decimals)[0,2] / 10 ** decimals
-    nbbox[1,2] = np.ceil(bbox * 10 ** decimals)[1,2] / 10 ** decimals
+    nbbox = np.round(raw_bbox, decimals)
+    nbbox[0,2] = np.floor(raw_bbox * 10 ** decimals)[0,2] / 10 ** decimals
+    nbbox[1,2] = np.ceil(raw_bbox * 10 ** decimals)[1,2] / 10 ** decimals
 
     return nbbox
diff --git a/test/test_utils.py b/test/test_utils.py
index 566c53f..0eca61f 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -27,6 +27,11 @@ def test_bbox(fix_data):
     res = np.array([fix_data.min(axis=0), fix_data.max(axis=0)])
     assert (utils.bbox(fix_data) == res).all()
 
+def test_fit_bbox(fix_data):
+    res = np.array([[0, 0, 0],
+                    [1, 1, 1]])
+    assert (utils.fit_bbox(fix_data) == res).all()
+
 def test_read(datadir):
     with open(datadir.join('first.txt')) as f:
         assert f.read() == 'hullo\n'