diff --git a/testing/mozharness/mozharness/mozilla/building/buildb2gbase.py b/testing/mozharness/mozharness/mozilla/building/buildb2gbase.py
index 5c7b955bafc2..3e30634c6038 100644
--- a/testing/mozharness/mozharness/mozilla/building/buildb2gbase.py
+++ b/testing/mozharness/mozharness/mozilla/building/buildb2gbase.py
@@ -193,7 +193,7 @@ class B2GBuildBaseScript(BuildbotMixin, MockMixin,
                 )
             else:
                 return None
-        return revision[0:12] if revision else None
+        return revision
 
     def query_gecko_config_path(self):
         conf_file = self.config.get('gecko_config')
diff --git a/testing/mozharness/mozharness/mozilla/building/buildbase.py b/testing/mozharness/mozharness/mozilla/building/buildbase.py
index c8231b390168..f6dfa0bcce9e 100755
--- a/testing/mozharness/mozharness/mozilla/building/buildbase.py
+++ b/testing/mozharness/mozharness/mozilla/building/buildbase.py
@@ -1138,7 +1138,7 @@ or run without that action (ie: --no-{action})"
                 revision = self.get_output_from_command(
                     hg + ['parent', '--template', '{node|short}'], cwd=source_path
                 )
-        return revision[0:12].encode('ascii', 'replace') if revision else None
+        return revision.encode('ascii', 'replace') if revision else None
 
     def _checkout_source(self):
         """use vcs_checkout to grab source needed for build."""
diff --git a/testing/mozharness/scripts/spidermonkey_build.py b/testing/mozharness/scripts/spidermonkey_build.py
index 60c20cbc2ed4..8cc31b43985d 100755
--- a/testing/mozharness/scripts/spidermonkey_build.py
+++ b/testing/mozharness/scripts/spidermonkey_build.py
@@ -220,7 +220,7 @@ class SpidermonkeyBuild(MockMixin,
             # None.
             revision = self.config.get('revision')
 
-        return revision[0:12] if revision else None
+        return revision
 
     def query_branch(self):
         if self.buildbot_config and 'properties' in self.buildbot_config: