diff --git a/core/views/expo.py b/core/views/expo.py
index 6ce9cb7..3e75e5e 100644
--- a/core/views/expo.py
+++ b/core/views/expo.py
@@ -305,8 +305,16 @@ def getmimetype(path):
     """Our own version rather than relying on what is provided by the python library. Note that when
     Apache or nginx is used to deliver /expofiles/ it will use it's own idea of mimetypes and
     not these.
+    
+    This sets the Content Type in the HTTP header, e.g.
+    Content-Type: text/html; charset=utf-8
     """
     path = str(path)
+    
+    if path.lower().endswith("gpx"):
+        return "application/octet-stream"  
+    if path.lower().endswith("kml"):
+        return "application/octet-stream"  
     if path.lower().endswith(".css"):
         return "text/css"
     if path.lower().endswith(".txt"):