1 files changed, 2 insertions, 0 deletions
diff --git a/boto/auth.py b/boto/auth.py
index 6012962a..bc8290d7 100644
--- a/boto/auth.py
+++ b/boto/auth.py
@@ -317,6 +317,8 @@ class HmacAuthV4Handler(AuthHandler, HmacKeys):
         for name, value in http_request.headers.items():
             lname = name.lower()
             if lname.startswith('x-amz'):
+                if isinstance(value, bytes):
+                    value = value.decode('utf-8')
                 headers_to_sign[name] = value
         return headers_to_sign