diff --git a/linkcheck/checker/httpurl.py b/linkcheck/checker/httpurl.py
index 088fc9b6..9ef4476a 100644
--- a/linkcheck/checker/httpurl.py
+++ b/linkcheck/checker/httpurl.py
@@ -589,8 +589,9 @@ class HttpUrl (urlbase.UrlBase, proxysupport.ProxySupport):
         """
         ptype = self.headers.get('Content-Type', 'application/octet-stream')
         if ";" in ptype:
+            # split off not needed extension info
             ptype = ptype.split(';')[0]
-        return ptype
+        return ptype.strip()
 
     def is_parseable (self):
         """