diff --git a/grid_recorder.py b/grid_recorder.py
index 0970b4a..5e66a03 100644
--- a/grid_recorder.py
+++ b/grid_recorder.py
@@ -98,7 +98,7 @@ class Configuration():
         self.channels = self.n_rows * self.n_cols + self.n_extra
 
     def create_file_structure(self):
-        start_str = ('%2.f_%2.f' % (self.start_clock[0], self.start_clock[1])).replace(' ', '0')
+        start_str = ('-%2.f_%2.f' % (self.start_clock[0], self.start_clock[1])).replace(' ', '0')
         self.path = os.path.join(self._base_path, self.now.strftime('-'.join(self.path_format.split('-')[:3])) + start_str)  # ToDo: Edit here
         if not os.path.exists(self.path):
             os.makedirs(self.path)