diff --git a/python_apps/pypo/liquidsoap_scripts/ls_lib.liq b/python_apps/pypo/liquidsoap_scripts/ls_lib.liq
index a044edc7c..e2123e26d 100644
--- a/python_apps/pypo/liquidsoap_scripts/ls_lib.liq
+++ b/python_apps/pypo/liquidsoap_scripts/ls_lib.liq
@@ -23,12 +23,19 @@ end
 # A function applied to each metadata chunk
 def append_title(m) =  
   log("Using stream_format #{!stream_metadata_type}")
-  if !stream_metadata_type == 1 then
-    [("title", "#{!show_name} - #{m['artist']} - #{m['title']}")]
-  elsif !stream_metadata_type == 2 then
-    [("title", "#{!station_name} - #{!show_name}")]
+
+  if list.mem_assoc("mapped", m) then
+    #protection against applying this function twice. It shouldn't be happening
+    #and bug file with Liquidsoap.
+    m
   else
-    [("title", "#{m['artist']} - #{m['title']}")]
+      if !stream_metadata_type == 1 then
+        [("title", "#{!show_name} - #{m['artist']} - #{m['title']}"), ("mapped", "true")]
+      elsif !stream_metadata_type == 2 then
+        [("title", "#{!station_name} - #{!show_name}"), ("mapped", "true")]
+      else
+        [("title", "#{m['artist']} - #{m['title']}"), ("mapped", "true")]
+      end
   end
 end
 
diff --git a/python_apps/pypo/liquidsoap_scripts/ls_script.liq b/python_apps/pypo/liquidsoap_scripts/ls_script.liq
index 4d6318529..36d85a372 100644
--- a/python_apps/pypo/liquidsoap_scripts/ls_script.liq
+++ b/python_apps/pypo/liquidsoap_scripts/ls_script.liq
@@ -73,11 +73,9 @@ create_source()
 queue = add(!sources, normalize=false)
 
 pair = insert_metadata(queue)
-f = fst(pair)
+dynamic_metadata_callback := fst(pair)
 queue = snd(pair)
 
-dynamic_metadata_callback := f
-
 output.dummy(fallible=true, queue)
 
 http = input.http_restart(id="http")