diff --git a/google/auth/iam.py b/google/auth/iam.py
index a8c9cce61..7367f02fc 100644
--- a/google/auth/iam.py
+++ b/google/auth/iam.py
@@ -35,10 +35,6 @@
     http_client.GATEWAY_TIMEOUT,
 }
 
-_DEFAULT_UNIVERSE_DOMAIN = ["googleapis.com"]
-
-_IAM_SCOPE = ["https://www.googleapis.com/auth/iam"]
-
 _IAM_SCOPE = ["https://www.googleapis.com/auth/iam"]
 
 _IAM_ENDPOINT = (
@@ -47,12 +43,12 @@
 )
 
 _IAM_SIGN_ENDPOINT = (
-    "https://iamcredentials.googleapis.com/v1/projects/-"
+    "https://iamcredentials.{}/v1/projects/-"
     + "/serviceAccounts/{}:signBlob"
 )
 
 _IAM_IDTOKEN_ENDPOINT = (
-    "https://iamcredentials.googleapis.com/v1/"
+    "https://iamcredentials.{}/v1/"
     + "projects/-/serviceAccounts/{}:generateIdToken"
 )
 
@@ -93,7 +89,7 @@ def _make_signing_request(self, message):
         message = _helpers.to_bytes(message)
 
         method = "POST"
-        url = _IAM_SIGN_ENDPOINT.format(self._service_account_email)
+        url = _IAM_SIGN_ENDPOINT.format(self._credentials.universe_domain, self._service_account_email)
         headers = {"Content-Type": "application/json"}
         body = json.dumps(
             {"payload": base64.b64encode(message).decode("utf-8")}
diff --git a/google/auth/impersonated_credentials.py b/google/auth/impersonated_credentials.py
index 6d6a4b8dc..614ce043e 100644
--- a/google/auth/impersonated_credentials.py
+++ b/google/auth/impersonated_credentials.py
@@ -278,11 +278,14 @@ def _update_token(self, request):
             body=body,
             iam_endpoint_override=self._iam_endpoint_override,
         )
+        
+    def get_iam_sign_endpoint(self):
+        return iam._IAM_SIGN_ENDPOINT.format(self.universe_domain, self._target_principal)
 
     def sign_bytes(self, message):
         from google.auth.transport.requests import AuthorizedSession
 
-        iam_sign_endpoint = iam._IAM_SIGN_ENDPOINT.format(self._target_principal)
+        iam_sign_endpoint = get_iam_sign_endpoint(self)
 
         body = {
             "payload": base64.b64encode(message).decode("utf-8"),
@@ -433,6 +436,7 @@ def refresh(self, request):
         from google.auth.transport.requests import AuthorizedSession
 
         iam_sign_endpoint = iam._IAM_IDTOKEN_ENDPOINT.format(
+            self._target_credentials.universe_domain,
             self._target_credentials.signer_email
         )
 
diff --git a/tests/test_impersonated_credentials.py b/tests/test_impersonated_credentials.py
index f467269e2..696401a38 100644
--- a/tests/test_impersonated_credentials.py
+++ b/tests/test_impersonated_credentials.py
@@ -124,6 +124,7 @@ def make_credentials(
         lifetime=LIFETIME,
         target_principal=TARGET_PRINCIPAL,
         iam_endpoint_override=None,
+        universe_domain=credentials.DEFAULT_UNIVERSE_DOMAIN
     ):
 
         return Credentials(
@@ -133,6 +134,7 @@ def make_credentials(
             delegates=self.DELEGATES,
             lifetime=lifetime,
             iam_endpoint_override=iam_endpoint_override,
+            universe_domain=universe_domain,
         )
 
     def test_get_cred_info(self):
@@ -144,6 +146,21 @@ def test_get_cred_info(self):
             "credential_source": "/path/to/file",
             "credential_type": "impersonated credentials",
             "principal": "impersonated@project.iam.gserviceaccount.com",
+            "iam_endpoint_override": None,
+        }
+    
+    def test_get_cred_info_universe_domain(self):
+        credentials = self.make_credentials(universe_domain="foo.bar")
+        assert not credentials.get_cred_info()
+
+        credentials._cred_file_path = "/path/to/file"
+        assert credentials.get_cred_info() == {
+            "credential_source": "/path/to/file",
+            "credential_type": "impersonated credentials",
+            "principal": "impersonated@project.iam.gserviceaccount.com",
+            "universe_domain": "foo.bar",
+            "iam_endpoint_override": "https://iamcredentials.foo.bar/v1/projects/-"
+        + "/serviceAccounts/impersonated@project.iam.gserviceaccount.com:generateAccessToken"
         }
 
     def test__make_copy_get_cred_info(self):
@@ -390,6 +407,11 @@ def test_signer(self):
     def test_signer_email(self):
         credentials = self.make_credentials(target_principal=self.TARGET_PRINCIPAL)
         assert credentials.signer_email == self.TARGET_PRINCIPAL
+        
+    def test_sign_endpoint(self):
+        credentials = self.make_credentials(universe_domain="foo.bar")
+        assert credentials.get_iam_sign_endpoint ==  "https://iamcredentials.foo.bar/v1/projects/-"
+    + "/serviceAccounts/impersonated@project.iam.gserviceaccount.com:signBlob"
 
     def test_service_account_email(self):
         credentials = self.make_credentials(target_principal=self.TARGET_PRINCIPAL)