diff --git a/hubspot/utils/signature.py b/hubspot/utils/signature.py
index 2982b331..cea8a724 100644
--- a/hubspot/utils/signature.py
+++ b/hubspot/utils/signature.py
@@ -2,13 +2,25 @@
 import hmac
 import hashlib
 
-from datetime import datetime
+from datetime import datetime, UTC, timedelta
 
 from hubspot.exceptions import InvalidSignatureVersionError, InvalidSignatureTimestampError
 
 
 class Signature:
-    MAX_ALLOWED_TIMESTAMP = 3000
+    MAX_ALLOWED_TIMESTAMP = 300
+
+    @staticmethod
+    def _is_timestamp_valid(timestamp: str) -> bool:
+        if timestamp is None:
+            return False
+        try:
+            timestamp_float = float(timestamp)
+            request_time = datetime.fromtimestamp(timestamp_float // 1000, tz=UTC)
+            current_time = datetime.now(UTC)
+            return current_time - request_time < timedelta(seconds=Signature.MAX_ALLOWED_TIMESTAMP)
+        except (ValueError, OverflowError):
+            return False
 
     @staticmethod
     def is_valid(
@@ -18,12 +30,12 @@ def is_valid(
         http_uri: str = None,
         http_method: str = "POST",
         signature_version: str = "v2",
-        timestamp: float = None
+        timestamp: str = None
     ) -> bool:
         if signature_version == "v3":
-            current_time = datetime.now()
-            if timestamp is None or current_time.timestamp() - timestamp > Signature.MAX_ALLOWED_TIMESTAMP:
+            if timestamp is None or not Signature._is_timestamp_valid(timestamp):
                 raise InvalidSignatureTimestampError(timestamp=timestamp)
+
         hashed_signature = Signature.get_signature(
             client_secret,
             request_body,
@@ -33,7 +45,7 @@ def is_valid(
             timestamp
         )
 
-        return signature == hashed_signature
+        return hmac.compare_digest(hashed_signature, signature)
 
     @staticmethod
     def get_signature(
@@ -42,7 +54,7 @@ def get_signature(
         signature_version: str,
         http_uri: str = None,
         http_method: str = "POST",
-        timestamp: float = None,
+        timestamp: str = None
     ) -> str:
         if signature_version == "v1":
             source_string = f"{client_secret}{request_body}"
@@ -54,10 +66,10 @@ def get_signature(
             source_string = f"{http_method}{http_uri}{request_body}{timestamp}"
             hashed_signature = base64.b64encode(
                 hmac.new(
-                        client_secret.encode("utf-8"),
-                        msg=source_string.encode("utf-8"),
-                        digestmod=hashlib.sha256
-                        ).digest()
+                    client_secret.encode("utf-8"),
+                    msg=source_string.encode("utf-8"),
+                    digestmod=hashlib.sha256
+                ).digest()
             ).decode()
             return hashed_signature
         else:
diff --git a/tests/spec/utils/test_signature.py b/tests/spec/utils/test_signature.py
index b0fe5510..9cbdb1c0 100644
--- a/tests/spec/utils/test_signature.py
+++ b/tests/spec/utils/test_signature.py
@@ -1,7 +1,5 @@
 import pytest
-
 from datetime import datetime
-
 from hubspot.exceptions import InvalidSignatureVersionError, InvalidSignatureTimestampError
 from hubspot.utils.signature import Signature
 
@@ -11,7 +9,7 @@
     "request_body": "{'example_field':'example_value'}",
     "url": "https://www.example.com/webhook_uri",
     "http_method": "POST",
-    "timestamp": 15000000,
+    "timestamp": str(int(datetime.now().timestamp() * 1000)),
 }
 
 
@@ -48,10 +46,12 @@ def test_get_signature__v2():
 
 def test_get_signature__v3():
     data = {
-            "signature": "HPW73RUtKmcYoEDADG0s6MmGFWUzWJKAW07r8RDgcQw=",
-            "signature_version": "v3"
-         }
+        "signature": "K36dawei4A+QBNolUOqo7s91KQDWQ5MXZ/QufNYuk/Y=",
+        "signature_version": "v3",
+    }
+
     data.update(TEST_DATA)
+    data["timestamp"] = "1693657560000"
 
     signature = Signature.get_signature(
         data["client_secret"],
@@ -66,13 +66,11 @@ def test_get_signature__v3():
 
 
 def test_get_signature__wrong_version():
-
     with pytest.raises(InvalidSignatureVersionError):
         Signature.get_signature(
             TEST_DATA["client_secret"],
             TEST_DATA["request_body"],
             "wrong_signature_version"
-
         )
 
 
@@ -84,7 +82,6 @@ def test_is_valid__v1():
         TEST_DATA["client_secret"],
         TEST_DATA["request_body"],
         signature_version="v1"
-
     )
 
     assert result
@@ -120,13 +117,12 @@ def test_is_valid__v2_get_method():
 
 
 def test_is_valid__v3():
-    timestamp = datetime.now().timestamp()
     signature = Signature.get_signature(
         TEST_DATA["client_secret"],
         TEST_DATA["request_body"],
         signature_version="v3",
         http_uri=TEST_DATA["url"],
-        timestamp=timestamp
+        timestamp=TEST_DATA["timestamp"]
     )
 
     result = Signature.is_valid(
@@ -135,7 +131,7 @@ def test_is_valid__v3():
         TEST_DATA["request_body"],
         signature_version="v3",
         http_uri=TEST_DATA["url"],
-        timestamp=timestamp
+        timestamp=TEST_DATA["timestamp"]
     )
 
     assert result
@@ -161,13 +157,14 @@ def test_is_valid__none_timestamp():
 
 
 def test_is_valid__expired_timestamp():
-    timestamp = datetime.now().timestamp()
+    expired_timestamp = str(int((datetime.now().timestamp() - Signature.MAX_ALLOWED_TIMESTAMP - 1) * 1000))
+
     signature = Signature.get_signature(
         TEST_DATA["client_secret"],
         TEST_DATA["request_body"],
         signature_version="v3",
         http_uri=TEST_DATA["url"],
-        timestamp=timestamp
+        timestamp=expired_timestamp
     )
 
     with pytest.raises(InvalidSignatureTimestampError):
@@ -177,5 +174,17 @@ def test_is_valid__expired_timestamp():
             TEST_DATA["request_body"],
             signature_version="v3",
             http_uri=TEST_DATA["url"],
-            timestamp=timestamp - Signature.MAX_ALLOWED_TIMESTAMP
+            timestamp=expired_timestamp
         )
+
+
+def test_is_timestamp_valid__valid_timestamp():
+    current_timestamp = str(int(datetime.now().timestamp() * 1000))
+
+    assert Signature._is_timestamp_valid(current_timestamp) is True
+
+
+def test_is_timestamp_valid__expired_timestamp():
+    expired_timestamp = str(int((datetime.now().timestamp() - Signature.MAX_ALLOWED_TIMESTAMP - 10) * 1000))
+
+    assert Signature._is_timestamp_valid(expired_timestamp) is False