diff --git a/src/pyFAI/integrator/fiber.py b/src/pyFAI/integrator/fiber.py
index 815a1b634..383c4ee8d 100644
--- a/src/pyFAI/integrator/fiber.py
+++ b/src/pyFAI/integrator/fiber.py
@@ -64,12 +64,20 @@ def sample_orientation(self):
 
     def parse_units(self, unit_ip, unit_oop, incident_angle=None, tilt_angle=None, sample_orientation=None):
         if unit_ip is None:
-            unit_ip = units.get_unit_fiber("qip_nm^-1")
+            unit_ip = units.get_unit_fiber(name="qip_nm^-1")
+        elif isinstance(unit_ip, str):
+            unit_ip = units.get_unit_fiber(name=unit_ip)
+        elif isinstance(unit_ip, units.UnitFiber):
+            ...
         else:
             unit_ip = units.to_unit(unit_ip)
 
         if unit_oop is None:
-            unit_oop = units.get_unit_fiber("qoop_nm^-1")
+            unit_oop = units.get_unit_fiber(name="qoop_nm^-1")
+        elif isinstance(unit_oop, str):
+            unit_oop = units.get_unit_fiber(name=unit_oop)
+        elif isinstance(unit_oop, units.UnitFiber):
+            ...
         else:
             unit_oop = units.to_unit(unit_oop)
 
diff --git a/src/pyFAI/units.py b/src/pyFAI/units.py
index 58ae3a93d..5c4515d9c 100644
--- a/src/pyFAI/units.py
+++ b/src/pyFAI/units.py
@@ -41,6 +41,7 @@
 __status__ = "production"
 __docformat__ = 'restructuredtext'
 
+import copy
 import logging
 logger = logging.getLogger(__name__)
 import numpy
@@ -990,7 +991,8 @@ def get_unit_fiber(name, incident_angle:float =0.0, tilt_angle:float =0.0, sampl
     :param float tilt angle: roll angle. Its rotation axis is orthogonal to the beam, the horizontal axis of the lab frame
     :param sample_orientation: 1-4, four different orientation of the fiber axis regarding the detector main axis, from 1 to 4 is +90º
     """
-    unit = RADIAL_UNITS.get(name, None)
+    unit = copy.deepcopy(RADIAL_UNITS.get(name, None))
+
     if unit is not None:
         unit.set_incident_angle(incident_angle)
         unit.set_tilt_angle(tilt_angle)