diff --git a/xpra/server/window/content_guesser.py b/xpra/server/window/content_guesser.py
index 5ee73324bf..73104e35e9 100644
--- a/xpra/server/window/content_guesser.py
+++ b/xpra/server/window/content_guesser.py
@@ -97,6 +97,8 @@ def load_content_type_defs() -> dict:
 def parse_content_types(lines) -> dict:
     defs = {}
     for line in lines:
+        if not line:
+            continue
         parts = line.rsplit("=", 1)
         #ie: "title:helloworld=text   #some comments here" -> "title:helloworld", "text   #some comments here"
         if len(parts)!=2: