1 files changed, 1 insertions, 1 deletions
diff --git a/bottle.py b/bottle.py
index 4a1e7c9..1fa6b2c 100644
--- a/bottle.py
+++ b/bottle.py
@@ -1405,7 +1405,7 @@ def _hkey(key):
 
 
 def _hval(value):
-    value = value if isinstance(value, unicode) else str(value)
+    value = tonat(value)
     if '\n' in value or '\r' in value or '\0' in value:
         raise ValueError("Header value must not contain control characters: %r" % value)
     return value