diff --git a/process/main.py b/process/main.py
index d6835f92c..ac0928d6f 100644
--- a/process/main.py
+++ b/process/main.py
@@ -366,7 +366,7 @@ def set_filenames(self, filepath_out):
         ).strip()
         self.set_input()
         data_structure.global_variables.output_prefix = (
-            ""
+            f"{Path(self.filepath).as_posix().strip()}/"
             if not self.filename_prefix
             else Path(self.filepath, self.filename_prefix).as_posix().strip()
         )