diff --git a/test/bytecode_2.7_run/05_string_constants.pyc b/test/bytecode_2.7_run/05_string_constants.pyc
new file mode 100644
index 000000000..0bc8f9e13
Binary files /dev/null and b/test/bytecode_2.7_run/05_string_constants.pyc differ
diff --git a/test/bytecode_3.6_run/05_string_constants.pyc b/test/bytecode_3.6_run/05_string_constants.pyc
new file mode 100644
index 000000000..70d68321e
Binary files /dev/null and b/test/bytecode_3.6_run/05_string_constants.pyc differ
diff --git a/test/simple_source/bug27+/05_string_constants.py b/test/simple_source/bug27+/05_string_constants.py
new file mode 100644
index 000000000..453a90161
--- /dev/null
+++ b/test/simple_source/bug27+/05_string_constants.py
@@ -0,0 +1,13 @@
+# See https://github.com/rocky/python-uncompyle6/issues/528
+# RUNNABLE!
+
+"""This program is self-checking!"""
+
+x = 1
+L = [239, 168, 254, 54, 235, 128, "fred"]
+D = {239: 240, 168:169, 54:55, 128:129, "fred":"wilma"}
+S = {239, 168, 254, 54, 235, 128, "fred"}
+
+assert L[6] == "fred"
+assert "fred" in S
+assert D["fred"] == "wilma"
diff --git a/uncompyle6/semantics/n_actions.py b/uncompyle6/semantics/n_actions.py
index 9234cea0f..8addb26f7 100644
--- a/uncompyle6/semantics/n_actions.py
+++ b/uncompyle6/semantics/n_actions.py
@@ -206,6 +206,22 @@ def n_classdef(self, node: SyntaxTree):
 
     n_classdefdeco2 = n_classdef
 
+    def format_const(self, elem):
+        """
+        Render one constant collection element (ADD_VALUE) to source text.
+
+        On 3.x the scanner already stores the element's source form (its
+        argrepr) in pattr, so emit that directly. On 2.x pattr holds the raw
+        value, so format it the way n_LOAD_CONST does. elem.attr is the
+        co_consts index on 2.x and must never be emitted as the value.
+        """
+        if self.version >= (3, 0):
+            return elem.pattr
+        data = elem.pattr
+        if isinstance(data, (float, complex)):
+            return better_repr(data, self.version)
+        return repr(data)
+
     def n_const_list(self, node: SyntaxTree):
         """
         prettyprint a constant dict, list, set or tuple.
@@ -242,13 +258,10 @@ def n_const_list(self, node: SyntaxTree):
                 assert elem.kind == "ADD_VALUE"
                 if elem.optype in ("local", "name"):
                     value = elem.attr
-                elif elem.optype == "const" and not isinstance(elem.attr, str):
-                    value = elem.attr
+                elif elem.optype == "const":
+                    value = self.format_const(elem)
                 else:
-                    try:
-                        value = "%r" % elem.pattr
-                    except Exception:
-                        value = elem.pattr
+                    value = elem.pattr
                 if elem.linestart is not None:
                     if elem.linestart != self.line_number:
                         next_indent = self.indent + INDENT_PER_LEVEL[:-1]
@@ -276,7 +289,7 @@ def n_const_list(self, node: SyntaxTree):
                     if elem.optype in ("local", "name"):
                         value = elem.attr
                     elif elem.optype == "const":
-                        value = elem.pattr
+                        value = self.format_const(elem)
                     else:
                         value = "%s" % repr(elem.attr)
                 else: