diff --git a/src/gam/__init__.py b/src/gam/__init__.py
index e0e8de38..ebb89d81 100755
--- a/src/gam/__init__.py
+++ b/src/gam/__init__.py
@@ -1086,9 +1086,10 @@ def getService(api, httpObj):
         controlflow.invalid_json_exit(disc_file)
 
 
-def buildGAPIObject(api):
+def buildGAPIObject(api, credentials=None):
     GM_Globals[GM_CURRENT_API_USER] = None
-    credentials = getValidOauth2TxtCredentials(api=getAPIVersion(api)[0])
+    if not credentials:
+        credentials = getValidOauth2TxtCredentials(api=getAPIVersion(api)[0])
     credentials.user_agent = GAM_INFO
     httpObj = transport.AuthorizedHttp(
         credentials, transport.create_http(cache=GM_Globals[GM_CACHE_DIR]))
diff --git a/src/gam/auth/signjwt.py b/src/gam/auth/signjwt.py
index cb324f32..cde0142e 100644
--- a/src/gam/auth/signjwt.py
+++ b/src/gam/auth/signjwt.py
@@ -5,10 +5,12 @@ import json
 import google.auth
 from google.auth._helpers import datetime_to_secs, scopes_to_string, utcnow
 import google.oauth2.service_account
-from googleapiclient.discovery import build
 
+import gam
 from gam import controlflow
 from gam import gapi
+from gam import transport
+from gam.var import GM_Globals, GM_CACHE_DIR
 
 _DEFAULT_TOKEN_LIFETIME_SECS = 3600  # 1 hour in seconds
 _GOOGLE_OAUTH2_TOKEN_ENDPOINT = "https://oauth2.googleapis.com/token"
@@ -75,7 +77,10 @@ class SignJwt(google.auth.crypt.Signer):
             credentials, _ = google.auth.default()
         except google.auth.exceptions.DefaultCredentialsError as e:
             controlflow.system_error_exit(2, e)
-        iamc = build('iamcredentials', 'v1', credentials=credentials)
+        httpObj = transport.AuthorizedHttp(
+                credentials,
+                transport.create_http(cache=GM_Globals[GM_CACHE_DIR]))
+        iamc = gam.getService('iamcredentials', httpObj)
         response = gapi.call(iamc.projects().serviceAccounts(),
                              'signJwt',
                              name=self.name,