diff --git a/deluge/httpdownloader.py b/deluge/httpdownloader.py
index 4e65d89cb..47d18f26c 100644
--- a/deluge/httpdownloader.py
+++ b/deluge/httpdownloader.py
@@ -106,6 +106,11 @@ def download_file(url, filename, callback=None, headers=None):
     :raises t.w.e.Error: for all other HTTP response errors (besides OK)
     """
     url = str(url)
+    filename = str(filename)
+    if headers:
+        for key, value in headers.items():
+            headers[str(key)] = str(value)
+
     scheme, host, port, path = client._parse(url)
     factory = HTTPDownloader(url, filename, callback, headers)
     if scheme == "https":
diff --git a/deluge/plugins/blocklist/blocklist/core.py b/deluge/plugins/blocklist/blocklist/core.py
index 523d5635f..264f9f8f0 100644
--- a/deluge/plugins/blocklist/blocklist/core.py
+++ b/deluge/plugins/blocklist/blocklist/core.py
@@ -229,7 +229,7 @@ class Core(CorePluginBase):
 
         headers = {}
         if self.config["last_update"] and not self.force_download:
-            headers['If-Modified-Since'] = str(self.config["last_update"])
+            headers['If-Modified-Since'] = self.config["last_update"]
 
         log.debug("Attempting to download blocklist %s" % url)
         log.debug("Sending headers: %s" % headers)
diff --git a/deluge/ui/web/json_api.py b/deluge/ui/web/json_api.py
index 209ae9a59..6ab6258c0 100644
--- a/deluge/ui/web/json_api.py
+++ b/deluge/ui/web/json_api.py
@@ -459,7 +459,7 @@ class WebApi(JSONComponent):
         log.debug("filename: %s", tmp_file)
         headers = {}
         if cookie:
-            headers["Cookie"] = str(cookie)
+            headers["Cookie"] = cookie
             log.debug("cookie: %s", cookie)
         return httpdownloader.download_file(url, tmp_file, headers=headers)