diff --git a/bin/bitbake-worker b/bin/bitbake-worker
index 4ad716975..b8dc9c862 100755
--- a/bin/bitbake-worker
+++ b/bin/bitbake-worker
@@ -296,7 +296,10 @@ def fork_off_task(cfg, data, databuilder, workerdata, extraconfigdata, runtask):
 
                 # exported_vars() returns a generator which *cannot* be passed to os.environ.update() 
                 # successfully. We also need to unset anything from the environment which shouldn't be there 
-                exports = bb.data.exported_vars(the_data)
+                # Iterating it expands each value, so materialise the generator before
+                # empty_environment() below: an expansion deferred past that point runs
+                # against the wiped environment, not the one bitbake started with.
+                exports = list(bb.data.exported_vars(the_data))
 
                 bb.utils.empty_environment()
                 for e, v in exports:
diff --git a/lib/bb/tests/data.py b/lib/bb/tests/data.py
index fd690a9e2..06c88ffc6 100644
--- a/lib/bb/tests/data.py
+++ b/lib/bb/tests/data.py
@@ -723,3 +723,45 @@ class EmitVar(unittest.TestCase):
         self.assertEqual(self.get_output(out), ['bad_chars="a\\"b \\',
                                                 'c\\`d \\',
                                                 'e\\$f"'])
+
+class ExportedVars(unittest.TestCase):
+    """bb.data.exported_vars() expands each value as it is iterated.
+
+    bitbake-worker's fork_off_task() therefore materialises the generator
+    with list() before it calls bb.utils.empty_environment(): an exported
+    variable whose value expands from the environment (e.g. a gitver-style
+    PV that runs git and needs the real PATH) has to be expanded while that
+    environment still exists. bitbake-worker runs on import (only its
+    version check sits behind a __main__ guard), so these tests reproduce
+    its sequence against bb.data and pin the behaviour the worker relies
+    on, not the worker itself.
+    """
+
+    def setUp(self):
+        self.saved_environment = dict(os.environ)
+        os.environ["BB_TEST_EXPORTED_VARS"] = "intact"
+
+        self.d = bb.data.init()
+        self.d.setVar("TESTEXPORT",
+                      "${@os.environ.get('BB_TEST_EXPORTED_VARS', 'wiped')}")
+        self.d.setVarFlag("TESTEXPORT", "export", "1")
+
+    def tearDown(self):
+        # empty_environment() wipes the environment of this process, not a
+        # copy of it, so put it back whatever the test did.
+        os.environ.clear()
+        os.environ.update(self.saved_environment)
+
+    def test_materialised_before_empty_environment(self):
+        # What bitbake-worker does: list() expands every value while the
+        # environment is still intact, so the wipe cannot reach them.
+        exports = list(bb.data.exported_vars(self.d))
+        bb.utils.empty_environment()
+        self.assertEqual(dict(exports)["TESTEXPORT"], "intact")
+
+    def test_lazy_generator_expands_after_empty_environment(self):
+        # Why the list() is required: a generator bound before the wipe but
+        # consumed after it expands against the wiped environment instead.
+        exports = bb.data.exported_vars(self.d)
+        bb.utils.empty_environment()
+        self.assertEqual(dict(exports)["TESTEXPORT"], "wiped")