diff --git a/src/orb/resources/webhooks.py b/src/orb/resources/webhooks.py
index 2c5e9c7c..48c321fa 100644
--- a/src/orb/resources/webhooks.py
+++ b/src/orb/resources/webhooks.py
@@ -56,7 +56,11 @@ def verify_signature(
         now = datetime.now(tz=timezone.utc)
 
         try:
-            timestamp = datetime.fromisoformat(msg_timestamp).astimezone()
+            timestamp = datetime.fromisoformat(msg_timestamp)
+            # If the timestamp doesn't have timezone info, assume it's UTC
+            if timestamp.tzinfo is None:
+                timestamp = timestamp.replace(tzinfo=timezone.utc)
+            timestamp = timestamp.astimezone()
         except Exception as err:
             raise ValueError("Invalid signature headers. Could not convert to timestamp") from err
 
@@ -140,7 +144,11 @@ def verify_signature(
         now = datetime.now(tz=timezone.utc)
 
         try:
-            timestamp = datetime.fromisoformat(msg_timestamp).astimezone()
+            timestamp = datetime.fromisoformat(msg_timestamp)
+            # If the timestamp doesn't have timezone info, assume it's UTC
+            if timestamp.tzinfo is None:
+                timestamp = timestamp.replace(tzinfo=timezone.utc)
+            timestamp = timestamp.astimezone()
         except Exception as err:
             raise ValueError("Invalid signature headers. Could not convert to timestamp") from err
 
diff --git a/tests/api_resources/test_webhooks.py b/tests/api_resources/test_webhooks.py
index ff269d5e..2ac0b7a1 100644
--- a/tests/api_resources/test_webhooks.py
+++ b/tests/api_resources/test_webhooks.py
@@ -4,7 +4,7 @@
 
 import os
 from typing import Any, cast
-from datetime import datetime, timedelta
+from datetime import datetime, timezone, timedelta
 
 import pytest
 import time_machine
@@ -18,7 +18,11 @@ class TestWebhooks:
     parametrize = pytest.mark.parametrize("client", [False, True], indirect=True, ids=["loose", "strict"])
 
     timestamp = "2024-03-27T15:42:29.551"
-    fake_now = datetime.fromisoformat(timestamp).astimezone()
+    # Fix: Ensure fake_now matches how webhook timestamps are now parsed (UTC assumption)
+    fake_now_dt = datetime.fromisoformat(timestamp)
+    if fake_now_dt.tzinfo is None:
+        fake_now_dt = fake_now_dt.replace(tzinfo=timezone.utc)
+    fake_now = fake_now_dt.astimezone()
 
     payload = """{"id": "o4mmewpfNNTnjfZc", "created_at": "2024-03-27T15:42:29+00:00", "type": "resource_event.test", "properties": {"message": "A test webhook from Orb. Happy testing!"}}"""
     signature = "9d25de966891ab0bc18754faf8d83d0980b44ae330fcc130b41a6cf3daf1f391"
@@ -106,12 +110,98 @@ def test_verify_signature(self, client: Orb) -> None:
                 secret=secret,
             )
 
+    def test_microsecond_precision_issue_fixed(self, client: Orb) -> None:
+        """Test that the webhook timestamp parsing issue is fixed for the reported examples."""
+        import hmac
+        import hashlib
+
+        secret = self.secret
+
+        # Test cases from the reported issue - these should all work now
+        test_cases = [
+            ("2025-08-08T21:35:11.531998+00:00", "2025-08-08T21:35:11.445"),
+            ("2025-08-08T21:32:02.585239+00:00", "2025-08-08T21:32:02.497"),
+            ("2025-08-08T21:35:42.810490+00:00", "2025-08-08T21:35:42.660"),
+        ]
+
+        for _, (system_time_str, webhook_timestamp) in enumerate(test_cases, 1):
+            system_time = datetime.fromisoformat(system_time_str)
+
+            # Generate the correct signature
+            to_sign = f"v1:{webhook_timestamp}:{self.payload}".encode("utf-8")
+            signature = hmac.new(secret.encode("utf-8"), to_sign, hashlib.sha256).hexdigest()
+
+            with time_machine.travel(system_time):
+                # This should now work without raising "Webhook timestamp is too new"
+                client.webhooks.verify_signature(
+                    payload=self.payload,
+                    headers={"X-Orb-Timestamp": webhook_timestamp, "X-Orb-Signature": f"v1={signature}"},
+                    secret=secret,
+                )
+
+                # Also test the unwrap method
+                result = client.webhooks.unwrap(
+                    payload=self.payload,
+                    headers={"X-Orb-Timestamp": webhook_timestamp, "X-Orb-Signature": f"v1={signature}"},
+                    secret=secret,
+                )
+                assert result is not None
+
+    def test_timezone_aware_timestamps_still_work(self, client: Orb) -> None:
+        """Test that webhook timestamps with explicit timezone info still work."""
+        import hmac
+        import hashlib
+        from datetime import timezone
+
+        secret = self.secret
+
+        # Test with explicit UTC timezone
+        system_time = datetime(2025, 8, 8, 21, 35, 11, 531998, tzinfo=timezone.utc)
+        webhook_timestamp = "2025-08-08T21:35:11.445+00:00"  # Explicit UTC
+
+        to_sign = f"v1:{webhook_timestamp}:{self.payload}".encode("utf-8")
+        signature = hmac.new(secret.encode("utf-8"), to_sign, hashlib.sha256).hexdigest()
+
+        with time_machine.travel(system_time):
+            client.webhooks.verify_signature(
+                payload=self.payload,
+                headers={"X-Orb-Timestamp": webhook_timestamp, "X-Orb-Signature": f"v1={signature}"},
+                secret=secret,
+            )
+
+    def test_webhook_timestamp_actually_too_new(self, client: Orb) -> None:
+        """Test that webhooks that are genuinely too new are still rejected."""
+        import hmac
+        import hashlib
+        from datetime import timezone
+
+        secret = self.secret
+
+        # Set system time to be much earlier than webhook timestamp (more than 5 minute tolerance)
+        system_time = datetime(2025, 8, 8, 21, 30, 0, 0, tzinfo=timezone.utc)
+        webhook_timestamp = "2025-08-08T21:36:00.000"  # 6 minutes later - should be rejected
+
+        to_sign = f"v1:{webhook_timestamp}:{self.payload}".encode("utf-8")
+        signature = hmac.new(secret.encode("utf-8"), to_sign, hashlib.sha256).hexdigest()
+
+        with time_machine.travel(system_time):
+            with pytest.raises(ValueError, match="Webhook timestamp is too new"):
+                client.webhooks.verify_signature(
+                    payload=self.payload,
+                    headers={"X-Orb-Timestamp": webhook_timestamp, "X-Orb-Signature": f"v1={signature}"},
+                    secret=secret,
+                )
+
 
 class TestAsyncWebhooks:
     parametrize = pytest.mark.parametrize("async_client", [False, True], indirect=True, ids=["loose", "strict"])
 
     timestamp = "2024-03-27T15:42:29.551"
-    fake_now = datetime.fromisoformat(timestamp).astimezone()
+    # Fix: Ensure fake_now matches how webhook timestamps are now parsed (UTC assumption)
+    fake_now_dt = datetime.fromisoformat(timestamp)
+    if fake_now_dt.tzinfo is None:
+        fake_now_dt = fake_now_dt.replace(tzinfo=timezone.utc)
+    fake_now = fake_now_dt.astimezone()
 
     payload = """{"id": "o4mmewpfNNTnjfZc", "created_at": "2024-03-27T15:42:29+00:00", "type": "resource_event.test", "properties": {"message": "A test webhook from Orb. Happy testing!"}}"""
     signature = "9d25de966891ab0bc18754faf8d83d0980b44ae330fcc130b41a6cf3daf1f391"