diff --git a/module_build_service/builder/MockModuleBuilder.py b/module_build_service/builder/MockModuleBuilder.py
index d4a3d888..0f610b67 100644
--- a/module_build_service/builder/MockModuleBuilder.py
+++ b/module_build_service/builder/MockModuleBuilder.py
@@ -468,7 +468,7 @@ class MockModuleBuilder(GenericBuilder):
                 self.enabled_modules = config_opts["module_enable"]
                 self.releasever = config_opts["releasever"]
 
-    def _write_mock_config(self):
+    def _write_mock_config(self, update_main=False):
         """
         Writes Mock config file to local file.
         """
@@ -483,11 +483,15 @@ class MockModuleBuilder(GenericBuilder):
             config = config.replace("$enabled_modules", str(self.enabled_modules))
             config = config.replace("$releasever", str(self.releasever))
 
-            # We write the most recent config to "mock.cfg", so thread-related
-            # configs can be later (re-)generated from it using _load_mock_config.
-            outfile = os.path.join(self.configdir, "mock.cfg")
-            with open(outfile, "w") as f:
-                f.write(config)
+
+            mock_cfg_path = os.path.join(self.configdir, "mock.cfg")
+            if update_main or not os.path.exists(mock_cfg_path):
+                # We write a config to "mock.cfg", so thread-related
+                # configs can be later (re-)generated from it using _load_mock_config.
+                with open(mock_cfg_path, "w") as f:
+                    f.write(config)
+
+            mtime = os.path.getmtime(mock_cfg_path)
 
             # Write the config to thread-related configuration file.
             outfile = os.path.join(
@@ -495,6 +499,8 @@ class MockModuleBuilder(GenericBuilder):
             with open(outfile, "w") as f:
                 f.write(config)
 
+            os.utime(outfile, (mtime, mtime))
+
     def buildroot_connect(self, groups):
         self._load_mock_config()
         self.groups = list(set().union(groups["build"], self.groups))
@@ -525,7 +531,7 @@ class MockModuleBuilder(GenericBuilder):
             if artifact and artifact.startswith("module-build-macros"):
                 self._load_mock_config()
                 self.groups.append("module-build-macros")
-                self._write_mock_config()
+                self._write_mock_config(update_main=True)
 
         events.scheduler.add(repos_done_handler, ("fake_msg", self.tag_name + "-build"))
 
@@ -586,7 +592,7 @@ class MockModuleBuilder(GenericBuilder):
                     baseurl = "file://" + repo_dir
 
             self._add_repo(repo_name, baseurl)
-        self._write_mock_config()
+        self._write_mock_config(update_main=True)
 
     def _send_build_change(self, state, source, build_id):
         from module_build_service.scheduler.handlers.components import (