diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1650aa77a..bbe9ba26f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@
 - #623, #819, #863 Support MatchOr, MatchSequence, MatchStar (@jheld, @lieryan)
 - #870 Add default implementation for is_dir() (@lieryan)
 - #872 Fix unicode handling in patchedast (@lieryan)
+- Fix patchedast end-quote detection for `'''` inside a double-quoted f-string
 
 # Release 1.14.0
 
diff --git a/rope/refactor/patchedast.py b/rope/refactor/patchedast.py
index 2a52fc924..8df52f088 100644
--- a/rope/refactor/patchedast.py
+++ b/rope/refactor/patchedast.py
@@ -385,14 +385,19 @@ def start_quote_char():
             return self.source[start : quote_pos + len(quote_char)]
 
         def end_quote_char():
-            possible_quotes = [
-                (self.source.source.rfind(q, start, end), q)
-                for q in reversed(QUOTE_CHARS)
-            ]
-            _, quote_pos, quote_char = max(
-                (len(q), pos, q) for pos, q in possible_quotes if pos != -1
+            # The closing delimiter is the quote char the f-string literally
+            # ends with -- NOT the longest quote char anywhere in the body.
+            # A ''' appearing inside a "..." f-string body must not be picked
+            # as the delimiter (issue: end_quote_char used max(len(q)) and
+            # mis-matched, producing a token that consume_joined_string could
+            # not locate).
+            for quote_char in QUOTE_CHARS:
+                if self.source.source[end - len(quote_char) : end] == quote_char:
+                    return self.source[end - len(quote_char) : end]
+            raise MismatchedTokenError(
+                f"f-string at line {self.lines.get_line_number(start)} does not"
+                " end with a quote delimiter"
             )
-            return self.source[end - len(quote_char) : end]
 
         QUOTE_CHARS = ['"""', "'''", '"', "'"]
         offset = self.source.offset
diff --git a/ropetest/refactor/patchedasttest.py b/ropetest/refactor/patchedasttest.py
index c014f6ed1..c50454035 100644
--- a/ropetest/refactor/patchedasttest.py
+++ b/ropetest/refactor/patchedasttest.py
@@ -326,6 +326,19 @@ def test_handling_format_strings_basic(self):
         checker.check_children("JoinedStr", ['f"', "abc", "FormattedValue", "", '"'])
         checker.check_children("FormattedValue", ["{", "", "Name", "", "}"])
 
+    @testutils.only_for_versions_higher("3.6")
+    def test_handling_format_strings_with_triple_quote_in_body(self):
+        # A double-quoted f-string whose body contains a ''' sequence must not
+        # confuse the end-quote detection (end_quote_char picked the longest
+        # quote in the body instead of the matching delimiter).
+        source = 'f"abc = \'\'\'{a}"\n'
+        ast_frag = patchedast.get_patched_ast(source, True)
+        checker = _ResultChecker(self, ast_frag)
+        checker.check_children(
+            "JoinedStr", ['f"', "abc = '''", "FormattedValue", "", '"']
+        )
+        checker.check_children("FormattedValue", ["{", "", "Name", "", "}"])
+
     @testutils.only_for_versions_higher("3.6")
     def test_handling_format_strings_with_implicit_join(self):
         source = '''"1" + rf'abc{a}' f"""xxx{b} """\n'''