diff --git a/src/ifcpatch/test/test_ConvertLengthUnit.py b/src/ifcpatch/test/test_ConvertLengthUnit.py
new file mode 100644
index 0000000000..e1d5ad2502
--- /dev/null
+++ b/src/ifcpatch/test/test_ConvertLengthUnit.py
@@ -0,0 +1,39 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+import ifcopenshell.util.unit
+import ifcpatch
+
+
+class TestConvertLengthUnit(test.bootstrap.IFC4):
+    # NOTE: conversion itself is covered by `ifcopenshell.util.unit.convert_file_length_units` tests
+    def test_run(self):
+        project = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcProject")
+        unit = ifcopenshell.api.run("unit.add_si_unit", self.file, unit_type="LENGTHUNIT", prefix="MILLI")
+        ifcopenshell.api.run("unit.assign_unit", self.file, units=[unit])
+        output = ifcpatch.execute(
+            {"input": "input.ifc", "file": self.file, "recipe": "ConvertLengthUnit", "arguments": ["METERS"]}
+        )
+        unit = ifcopenshell.util.unit.get_project_unit(output, "LENGTHUNIT")
+        assert unit.Prefix == None
+
+
+class TestConvertLengthUnitIFC2X3(test.bootstrap.IFC2X3, TestConvertLengthUnit):
+    pass