diff --git a/src/snapred/backend/recipe/ReductionRecipe.py b/src/snapred/backend/recipe/ReductionRecipe.py
index 9fe863a0a..fb679cd06 100644
--- a/src/snapred/backend/recipe/ReductionRecipe.py
+++ b/src/snapred/backend/recipe/ReductionRecipe.py
@@ -114,7 +114,7 @@ def _prepareUnfocusedData(self, workspace: WorkspaceName, mask: Optional[Workspa
         
         self.mantidSnapper.ConvertUnits(
             f"Converting unfocused data to {units} units",
-            InputWorkspace=workspace,
+            InputWorkspace=self.unfocWs,
             OutputWorkspace=self.unfocWs,
             Target=units,
         )
diff --git a/tests/unit/backend/recipe/test_ReductionRecipe.py b/tests/unit/backend/recipe/test_ReductionRecipe.py
index ffd923c5f..b51956843 100644
--- a/tests/unit/backend/recipe/test_ReductionRecipe.py
+++ b/tests/unit/backend/recipe/test_ReductionRecipe.py
@@ -91,7 +91,7 @@ def test_prepareUnfocusedData(self):
         recipe._prepareUnfocusedData(workspace, None, units)
         outputWs = wng.run().runNumber("555").lite(True).unit(wng.Units.DSP).group(wng.Groups.UNFOC).build()
         recipe.mantidSnapper.ConvertUnits.assert_called_once_with(
-            msg, InputWorkspace=workspace, OutputWorkspace=outputWs, Target=units
+            msg, InputWorkspace=outputWs, OutputWorkspace=outputWs, Target=units
         )
         recipe.mantidSnapper.executeQueue.assert_called()
         recipe.mantidSnapper.reset_mock()
@@ -101,7 +101,7 @@ def test_prepareUnfocusedData(self):
         recipe._prepareUnfocusedData(workspace, None, units)
         outputWs = wng.run().runNumber("555").lite(True).unit(wng.Units.QSP).group(wng.Groups.UNFOC).build()
         recipe.mantidSnapper.ConvertUnits.assert_called_once_with(
-            msg, InputWorkspace=workspace, OutputWorkspace=outputWs, Target=units
+            msg, InputWorkspace=outputWs, OutputWorkspace=outputWs, Target=units
         )
         recipe.mantidSnapper.executeQueue.assert_called()
         recipe.mantidSnapper.reset_mock()
@@ -111,7 +111,7 @@ def test_prepareUnfocusedData(self):
         recipe._prepareUnfocusedData(workspace, None, units)
         outputWs = wng.run().runNumber("555").lite(True).unit(wng.Units.LAM).group(wng.Groups.UNFOC).build()
         recipe.mantidSnapper.ConvertUnits.assert_called_once_with(
-            msg, InputWorkspace=workspace, OutputWorkspace=outputWs, Target=units
+            msg, InputWorkspace=outputWs, OutputWorkspace=outputWs, Target=units
         )
         recipe.mantidSnapper.executeQueue.assert_called()
         recipe.mantidSnapper.reset_mock()
@@ -121,7 +121,7 @@ def test_prepareUnfocusedData(self):
         recipe._prepareUnfocusedData(workspace, None, units)
         outputWs = wng.run().runNumber("555").lite(True).unit(wng.Units.TOF).group(wng.Groups.UNFOC).build()
         recipe.mantidSnapper.ConvertUnits.assert_called_once_with(
-            msg, InputWorkspace=workspace, OutputWorkspace=outputWs, Target=units
+            msg, InputWorkspace=outputWs, OutputWorkspace=outputWs, Target=units
         )
         recipe.mantidSnapper.executeQueue.assert_called()
         recipe.mantidSnapper.reset_mock()
@@ -152,7 +152,7 @@ def test_prepareUnfocusedData_masking(self):
         )
         recipe.mantidSnapper.ConvertUnits.assert_called_once_with(
             f"Converting unfocused data to {units} units",
-            InputWorkspace=workspace,
+            InputWorkspace=outputWs,
             OutputWorkspace=outputWs,
             Target=units
         )