diff --git a/module_build_service/utils/submit.py b/module_build_service/utils/submit.py
index 4a759333..761868ee 100644
--- a/module_build_service/utils/submit.py
+++ b/module_build_service/utils/submit.py
@@ -683,7 +683,7 @@ def submit_module_build(username, mmd, params):
                 log.debug('Found %d previous scratch module build context(s): %s',
                           scrmods.count(), ",".join(scrmod_contexts))
                 # append incrementing counter to context
-                context_suffix = '.' + str(scrmods.count() + 1)
+                context_suffix = '_' + str(scrmods.count() + 1)
                 mmd.set_context(mmd.get_context() + context_suffix)
             log.debug('Creating new module build')
             module = models.ModuleBuild.create(
diff --git a/tests/test_build/test_build.py b/tests/test_build/test_build.py
index ce497e38..35124f67 100644
--- a/tests/test_build/test_build.py
+++ b/tests/test_build/test_build.py
@@ -1236,7 +1236,7 @@ class TestBuild:
         module_build_id = data['id']
         module_build = models.ModuleBuild.query.filter_by(id=module_build_id).one()
         # make sure scratch build has context with unique suffix
-        assert module_build.context == '9c690d0e.1'
+        assert module_build.context == '9c690d0e_1'
 
     @patch('module_build_service.auth.get_user', return_value=user)
     @patch('module_build_service.scm.SCM')