diff --git a/osc/core.py b/osc/core.py
index 73d7e966..22125891 100644
--- a/osc/core.py
+++ b/osc/core.py
@@ -3666,7 +3666,7 @@ class metafile:
 
         if not isinstance(input, list):
             input = [input]
-        if isinstance(input[0], str):
+        if input and isinstance(input[0], str):
             input_as_str = ''.join(input)
         else:
             open_mode = 'wb'