diff --git a/django/core/mail.py b/django/core/mail.py
index b60757366f..78a1ec6192 100644
--- a/django/core/mail.py
+++ b/django/core/mail.py
@@ -71,10 +71,11 @@ class BadHeaderError(ValueError):
 
 def forbid_multi_line_headers(name, val):
     """Forbids multi-line headers, to prevent header injection."""
+    val = force_unicode(val)
     if '\n' in val or '\r' in val:
         raise BadHeaderError("Header values can't contain newlines (got %r for header %r)" % (val, name))
     try:
-        val = force_unicode(val).encode('ascii')
+        val = val.encode('ascii')
     except UnicodeEncodeError:
         if name.lower() in ('to', 'from', 'cc'):
             result = []
@@ -84,7 +85,7 @@ def forbid_multi_line_headers(name, val):
                 result.append(formataddr((nm, str(addr))))
             val = ', '.join(result)
         else:
-            val = Header(force_unicode(val), settings.DEFAULT_CHARSET)
+            val = Header(val, settings.DEFAULT_CHARSET)
     return name, val
 
 class SafeMIMEText(MIMEText):
diff --git a/tests/regressiontests/mail/tests.py b/tests/regressiontests/mail/tests.py
index 9d2e2abe96..be59234342 100644
--- a/tests/regressiontests/mail/tests.py
+++ b/tests/regressiontests/mail/tests.py
@@ -3,6 +3,7 @@ r"""
 # Tests for the django.core.mail.
 
 >>> from django.core.mail import EmailMessage
+>>> from django.utils.translation import ugettext_lazy
 
 # Test normal ascii character case:
 
@@ -36,6 +37,12 @@ r"""
 >>> message = email.message()
 Traceback (most recent call last):
     ...
-BadHeaderError: Header values can't contain newlines (got 'Subject\nInjection Test' for header 'Subject')
+BadHeaderError: Header values can't contain newlines (got u'Subject\nInjection Test' for header 'Subject')
+
+>>> email = EmailMessage(ugettext_lazy('Subject\nInjection Test'), 'Content', 'from@example.com', ['to@example.com'])
+>>> message = email.message()
+Traceback (most recent call last):
+    ...
+BadHeaderError: Header values can't contain newlines (got u'Subject\nInjection Test' for header 'Subject')
 
 """