diff --git a/src/newrelic_telemetry_sdk/harvester.py b/src/newrelic_telemetry_sdk/harvester.py
index 4fc29c0..e226e7a 100644
--- a/src/newrelic_telemetry_sdk/harvester.py
+++ b/src/newrelic_telemetry_sdk/harvester.py
@@ -64,7 +64,7 @@ def __init__(self, client, batch, harvest_interval=5):
         self.client = client
         self.batch = batch
         self.harvest_interval = harvest_interval
-        self._harvest_interval_start = 0
+        self._harvest_interval_start = None
         self._shutdown = self.EVENT_CLS()
 
     def _send(self):
@@ -83,11 +83,13 @@ def _send(self):
 
     def _wait_for_harvest(self):
         """Tracks and adjusts time required to maintain the harvest interval"""
-        current_time = time.time()
-        interval_start = self._harvest_interval_start or current_time
+        current_time = time.monotonic()
+        interval_start = self._harvest_interval_start
+        if interval_start is None:
+            interval_start = current_time
         timeout = max(self.harvest_interval - (current_time - interval_start), 0)
         shutdown = self._shutdown.wait(timeout)
-        self._harvest_interval_start = time.time()
+        self._harvest_interval_start = time.monotonic()
         return shutdown
 
     def run(self):
diff --git a/tests/test_harvester.py b/tests/test_harvester.py
index 0059c0f..8df1983 100644
--- a/tests/test_harvester.py
+++ b/tests/test_harvester.py
@@ -202,7 +202,7 @@ def _wait(t):
         timeout.append(t)
         return True
 
-    monkeypatch.setattr(time, "time", _time, raising=True)
+    monkeypatch.setattr(time, "monotonic", _time, raising=True)
     harvester._shutdown.wait = _wait
 
     # First call should result in full timeout
@@ -217,3 +217,20 @@ def _wait(t):
 def test_defaults(harvester):
     assert harvester.daemon is True
     assert harvester.harvest_interval == 5
+
+
+@pytest.mark.parametrize("clock_change", [-3600, 3600])
+def test_harvest_interval_ignores_wall_clock_changes(harvester, monkeypatch, clock_change):
+    wall_time = [10000]
+    elapsed_time = [100]
+    timeouts = []
+    monkeypatch.setattr(time, "time", lambda: wall_time[0])
+    monkeypatch.setattr(time, "monotonic", lambda: elapsed_time[0])
+    harvester._shutdown.wait = timeouts.append
+
+    harvester._wait_for_harvest()
+    wall_time[0] += clock_change
+    elapsed_time[0] += 2
+    harvester._wait_for_harvest()
+
+    assert timeouts == [5, 3]