diff --git a/kas/config.py b/kas/config.py
index 236d106..091e727 100644
--- a/kas/config.py
+++ b/kas/config.py
@@ -41,23 +41,22 @@ class Config:
         self._override_target = target
         self._override_task = task
         self._config = {}
-        if filename:
-            self.filenames = [os.path.abspath(configfile)
-                              for configfile in filename.split(':')]
-            self.top_repo_path = Repo.get_root_path(
-                os.path.dirname(self.filenames[0]))
+        if not filename:
+            filename = os.path.join(ctx.kas_work_dir, CONFIG_YAML_FILE)
 
-            repo_paths = [Repo.get_root_path(os.path.dirname(configfile),
-                                             fallback=False)
-                          for configfile in self.filenames]
+        self.filenames = [os.path.abspath(configfile)
+                          for configfile in filename.split(':')]
+        self.top_repo_path = Repo.get_root_path(
+            os.path.dirname(self.filenames[0]))
 
-            if len(set(repo_paths)) > 1:
-                raise IncludeException('All concatenated config files must '
-                                       'belong to the same repository or all '
-                                       'must be outside of versioning control')
-        else:
-            self.filenames = [os.path.join(ctx.kas_work_dir, CONFIG_YAML_FILE)]
-            self.top_repo_path = Repo.get_root_path(ctx.kas_work_dir)
+        repo_paths = [Repo.get_root_path(os.path.dirname(configfile),
+                                         fallback=False)
+                      for configfile in self.filenames]
+
+        if len(set(repo_paths)) > 1:
+            raise IncludeException('All concatenated config files must '
+                                   'belong to the same repository or all '
+                                   'must be outside of versioning control')
 
         self.handler = IncludeHandler(self.filenames, self.top_repo_path)
         self.repo_dict = self._get_repo_dict()