diff --git a/test/bytecode_3.6_run/01_fstring.pyc b/test/bytecode_3.6_run/01_fstring.pyc
index 8f6a2a1d..54711a34 100644
Binary files a/test/bytecode_3.6_run/01_fstring.pyc and b/test/bytecode_3.6_run/01_fstring.pyc differ
diff --git a/test/simple_source/bug36/01_fstring.py b/test/simple_source/bug36/01_fstring.py
index c03aaa79..0b753075 100644
--- a/test/simple_source/bug36/01_fstring.py
+++ b/test/simple_source/bug36/01_fstring.py
@@ -17,3 +17,10 @@ x = f"{k}={v!r}"
 y = f"functools.{x}({', '.join(v)})"
 assert x == "1=['2']"
 assert y == "functools.1=['2'](2)"
+
+# From 3.6 http/client.py
+# Bug is in handling  X
+chunk = ['a', 'b', 'c']
+chunk2 = 'd'
+chunk = f'{len(chunk):X}' + chunk2
+assert chunk == '3d'
diff --git a/uncompyle6/parsers/parse36.py b/uncompyle6/parsers/parse36.py
index 1225bb68..ef0dee17 100644
--- a/uncompyle6/parsers/parse36.py
+++ b/uncompyle6/parsers/parse36.py
@@ -184,8 +184,17 @@ class Python36Parser(Python35Parser):
                     self.add_unique_doc_rules(rules_str, customize)
             elif opname == 'FORMAT_VALUE':
                 rules_str = """
-                    expr ::= fstring_single
-                    fstring_single ::= expr FORMAT_VALUE
+                    expr            ::= fstring_single
+                    fstring_single  ::= expr FORMAT_VALUE
+                    expr            ::= fstring_expr
+                    fstring_expr    ::= expr FORMAT_VALUE
+
+                    # FIXME: need to look inside FORMAT_VALUE to see if 4
+                    fstring_single  ::= expr expr FORMAT_VALUE
+                    str             ::= LOAD_CONST
+                    formatted_value ::= fstring_expr
+                    formatted_value ::= str
+
                 """
                 self.add_unique_doc_rules(rules_str, customize)
             elif opname == 'MAKE_FUNCTION_8':
@@ -233,12 +242,6 @@ class Python36Parser(Python35Parser):
                 v = token.attr
                 joined_str_n = "formatted_value_%s" % v
                 rules_str = """
-                    expr            ::= fstring_expr
-                    fstring_expr    ::= expr FORMAT_VALUE
-                    str             ::= LOAD_CONST
-                    formatted_value ::= fstring_expr
-                    formatted_value ::= str
-
                     expr                 ::= fstring_multi
                     fstring_multi        ::= joined_str BUILD_STRING
                     joined_str           ::= formatted_value+
diff --git a/uncompyle6/semantics/customize36.py b/uncompyle6/semantics/customize36.py
index 5b283ad1..f2a3bf1f 100644
--- a/uncompyle6/semantics/customize36.py
+++ b/uncompyle6/semantics/customize36.py
@@ -324,7 +324,7 @@ def customize_for_version36(self, version):
     self.call36_dict = call36_dict
 
 
-    FSTRING_CONVERSION_MAP = {1: '!s', 2: '!r', 3: '!a'}
+    FSTRING_CONVERSION_MAP = {1: '!s', 2: '!r', 3: '!a', 'X':':X'}
 
     def n_except_suite_finalize(node):
         if node[1] == 'returns' and self.hide_internal:
@@ -351,7 +351,12 @@ def customize_for_version36(self, version):
     self.n_formatted_value = n_formatted_value
 
     def f_conversion(node):
-        node.conversion = FSTRING_CONVERSION_MAP.get(node.data[1].attr, '')
+        fmt_node = node.data[1]
+        if fmt_node == 'expr' and fmt_node[0] == 'LOAD_CONST':
+            data = fmt_node[0].attr
+        else:
+            data = fmt_node
+        node.conversion = FSTRING_CONVERSION_MAP.get(data, '')
 
     def fstring_expr(node):
         f_conversion(node)