diff --git a/tests/unit/macaroons/test_caveats.py b/tests/unit/macaroons/test_caveats.py
index 052a6d9ede2a..5f0a24fbb2e5 100644
--- a/tests/unit/macaroons/test_caveats.py
+++ b/tests/unit/macaroons/test_caveats.py
@@ -11,13 +11,20 @@
 # limitations under the License.
 
 import json
+import time
 
 import pretend
 import pytest
 
 from pymacaroons.exceptions import MacaroonInvalidSignatureException
 
-from warehouse.macaroons.caveats import Caveat, InvalidMacaroonError, V1Caveat, Verifier
+from warehouse.macaroons.caveats import (
+    Caveat,
+    ExpiryCaveat,
+    InvalidMacaroonError,
+    V1Caveat,
+    Verifier,
+)
 
 from ...common.db.packaging import ProjectFactory
 
@@ -95,6 +102,56 @@ def test_verify_project(self, db_request):
         assert caveat(json.dumps(predicate)) is True
 
 
+class TestExpiryCaveat:
+    @pytest.mark.parametrize(
+        "predicate",
+        [
+            # invalid JSON
+            "invalid json",
+            # missing nbf and exp
+            '{"missing": "values"}',
+            # nbf and exp present, but null
+            '{"nbf": null, "exp": null}',
+            # nbf and exp present, but empty
+            '{"nbf": "", "exp": ""}',
+            # valid JSON, but wrong type
+            "[]",
+        ],
+    )
+    def test_verify_invalid_predicates(self, predicate):
+        verifier = pretend.stub()
+        caveat = ExpiryCaveat(verifier)
+
+        assert not caveat(predicate)
+
+    def test_verify_not_before(self):
+        verifier = pretend.stub()
+        caveat = ExpiryCaveat(verifier)
+
+        not_before = int(time.time()) + 60
+        expiry = not_before + 60
+        predicate = json.dumps({"exp": expiry, "nbf": not_before})
+        assert not caveat(predicate)
+
+    def test_verify_already_expired(self):
+        verifier = pretend.stub()
+        caveat = ExpiryCaveat(verifier)
+
+        not_before = int(time.time()) - 10
+        expiry = not_before - 5
+        predicate = json.dumps({"exp": expiry, "nbf": not_before})
+        assert not caveat(predicate)
+
+    def test_verify_ok(self):
+        verifier = pretend.stub()
+        caveat = ExpiryCaveat(verifier)
+
+        not_before = int(time.time()) - 10
+        expiry = int(time.time()) + 60
+        predicate = json.dumps({"exp": expiry, "nbf": not_before})
+        assert caveat(predicate)
+
+
 class TestVerifier:
     def test_creation(self):
         macaroon = pretend.stub()
diff --git a/warehouse/macaroons/caveats.py b/warehouse/macaroons/caveats.py
index accb743b8a3d..4edc765b01ba 100644
--- a/warehouse/macaroons/caveats.py
+++ b/warehouse/macaroons/caveats.py
@@ -11,6 +11,7 @@
 # limitations under the License.
 
 import json
+import time
 
 import pymacaroons
 
@@ -73,6 +74,25 @@ def verify(self, predicate):
         return self.verify_projects(projects)
 
 
+class ExpiryCaveat(Caveat):
+    def verify(self, predicate):
+        try:
+            data = json.loads(predicate)
+            expiry = data["exp"]
+            not_before = data["nbf"]
+        except (KeyError, ValueError, TypeError):
+            return False
+
+        if not expiry or not not_before:
+            return False
+
+        now = int(time.time())
+        if now < not_before or now >= expiry:
+            return False
+
+        return True
+
+
 class Verifier:
     def __init__(self, macaroon, context, principals, permission):
         self.macaroon = macaroon
@@ -83,6 +103,7 @@ def __init__(self, macaroon, context, principals, permission):
 
     def verify(self, key):
         self.verifier.satisfy_general(V1Caveat(self))
+        self.verifier.satisfy_general(ExpiryCaveat(self))
 
         try:
             return self.verifier.verify(self.macaroon, key)