diff --git a/Lib/email/_header_value_parser.py b/Lib/email/_header_value_parser.py
--- a/Lib/email/_header_value_parser.py
+++ b/Lib/email/_header_value_parser.py
@@ -2742,12 +2742,21 @@
         if value and value[0] != "'":
             token, value = get_attrtext(value)
             appendto.append(token)
-            param.lang = token.value
-            if not value or value[0] != "'":
-                raise errors.HeaderParseError("Expected RFC2231 char/lang encoding "
-                                  "delimiter, but found {}".format(value))
-        appendto.append(ValueTerminal("'", 'RFC2231 delimiter'))
-        value = value[1:]
+            if value and value[0] == "'":
+                param.lang = token.value
+                appendto.append(ValueTerminal("'", 'RFC2231 delimiter'))
+                value = value[1:]
+            else:
+                # XXX this recovers for only a small subset of the possible
+                # bad data.  Need to extend the error recovery.
+                if value:
+                    param.defects.append(errors.InvalidHeaderDefect(
+                        "Expected RFC2231 char/lang encoding "
+                        "delimiter, but found {}".format(value)))
+                else:
+                    param.defects.append(errors.InvalidHeaderDefect(
+                        "Expected RFC2231 char/lang encoding "
+                        "delimiter, but found end of parameter"))
     if remainder is not None:
         # Treat the rest of value as bare quoted string content.
         v = Value()
@@ -2774,7 +2783,7 @@
     the formal RFC grammar, but it is more convenient for us for the set of
     parameters to be treated as its own TokenList.
 
-    This is 'parse' routine because it consumes the reminaing value, but it
+    This is a 'parse' routine because it consumes the remaining value, but it
     would never be called to parse a full header.  Instead it is called to
     parse everything after the non-parameter value of a specific MIME header.
 
diff --git a/Lib/email/utils.py b/Lib/email/utils.py
--- a/Lib/email/utils.py
+++ b/Lib/email/utils.py
@@ -337,6 +337,10 @@
     # object.  We do not want bytes() normal utf-8 decoder, we want a straight
     # interpretation of the string as character bytes.
     charset, language, text = value
+    if charset is None:
+        # Issue 17369: if charset/lang is None, decode_rfc2231 couldn't parse
+        # the value, so use the fallback_charset.
+        charset = fallback_charset
     rawbytes = bytes(text, 'raw-unicode-escape')
     try:
         return str(rawbytes, charset, errors)
diff --git a/Lib/test/test_email/test_email.py b/Lib/test/test_email/test_email.py
--- a/Lib/test/test_email/test_email.py
+++ b/Lib/test/test_email/test_email.py
@@ -4956,6 +4956,26 @@
         self.assertFalse(isinstance(param, tuple))
         self.assertEqual(param, "us-ascii'en-us'Frank's Document")
 
+    def test_rfc2231_missing_tick(self):
+        m = '''\
+Content-Disposition: inline;
+\tfilename*0*="'This%20is%20broken";
+'''
+        msg = email.message_from_string(m)
+        self.assertEqual(
+            msg.get_filename(),
+            "'This is broken")
+
+    def test_rfc2231_missing_tick_with_encoded_non_ascii(self):
+        m = '''\
+Content-Disposition: inline;
+\tfilename*0*="'This%20is%E2broken";
+'''
+        msg = email.message_from_string(m)
+        self.assertEqual(
+            msg.get_filename(),
+            "'This is\ufffdbroken")
+
     # test_headerregistry.TestContentTypeHeader.rfc2231_single_quotes_inside_quotes
     def test_rfc2231_no_extended_values(self):
         eq = self.assertEqual
diff --git a/Lib/test/test_email/test_headerregistry.py b/Lib/test/test_email/test_headerregistry.py
--- a/Lib/test/test_email/test_headerregistry.py
+++ b/Lib/test/test_email/test_headerregistry.py
@@ -556,6 +556,26 @@
              ' name*1=" Document"\n'),
              ),
 
+        # Issue 17369
+        'rfc2231_only_one_leading_single_quote': (
+            'text/plain; NAME*0*="\'This%20is%20broken"',
+            'text/plain',
+            'text',
+            'plain',
+            {'name': "'This is broken"},
+            [errors.InvalidHeaderDefect],
+            'text/plain; NAME="\'This is broken"'),
+
+        # Issue 17369
+        'rfc2231_only_one_single_quote_with_encoded_non_ascii': (
+            'text/plain; NAME*0*="\'This%20is%E2broken"',
+            'text/plain',
+            'text',
+            'plain',
+            {'name': "'This is\ufffdbroken"},
+            [errors.InvalidHeaderDefect],
+            'text/plain; NAME="\'This is%E2broken"'),
+
         'rfc2231_no_language_or_charset': (
             'text/plain; NAME*0*=english_is_the_default.html',
             'text/plain',