diff --git a/perfkitbenchmarker/sample.py b/perfkitbenchmarker/sample.py
index 90f8da5873..dece5c1298 100644
--- a/perfkitbenchmarker/sample.py
+++ b/perfkitbenchmarker/sample.py
@@ -137,7 +137,7 @@ def __new__(
       timestamp = time.time()
 
     metadata = metadata or {}
-    metadata = metadata.copy()
+    metadata = dict(metadata)
     return super().__new__(
         cls,
         metric,
diff --git a/tests/sample_test.py b/tests/sample_test.py
index e983eeb3d3..f60f0332bf 100644
--- a/tests/sample_test.py
+++ b/tests/sample_test.py
@@ -15,6 +15,7 @@
 
 import unittest
 
+import immutabledict
 from perfkitbenchmarker import sample
 
 
@@ -61,6 +62,16 @@ def testValuesShouldBeFloats(self):
     self.assertIsInstance(instance.value, float)
     self.assertEqual(1.0, instance.value)
 
+  def testImmutableMetadataConvertedToDict(self):
+    metadata = immutabledict.immutabledict({'origin': 'unit test'})
+    instance = sample.Sample(
+        metric='Test', value=1.0, unit='Mbps', metadata=metadata
+    )
+    self.assertIsInstance(instance.metadata, dict)
+    self.assertNotIsInstance(instance.metadata, immutabledict.immutabledict)
+    instance.metadata['new_key'] = 'new_value'
+    self.assertEqual(instance.metadata['new_key'], 'new_value')
+
 
 class TestPercentileCalculator(unittest.TestCase):