diff --git a/test/bytecode_3.6/09_long_whilestmt.pyc b/test/bytecode_3.6/09_long_whilestmt.pyc
new file mode 100644
index 00000000..7612eb31
Binary files /dev/null and b/test/bytecode_3.6/09_long_whilestmt.pyc differ
diff --git a/test/simple_source/bug36/09_long_whilestmt.py b/test/simple_source/bug36/09_long_whilestmt.py
new file mode 100644
index 00000000..1cf98b6b
--- /dev/null
+++ b/test/simple_source/bug36/09_long_whilestmt.py
@@ -0,0 +1,74 @@
+# From https://github.com/rocky/python-uncompyle6/issues/420
+# Related to EXTENDED_ARG in whilestmt
+ERRPR_CODE_DEFINE = {}  # Remove this and things works
+
+try:
+    print()
+except Exception:
+    var1 = 0
+    var2 = 1
+    if var1 or var2:
+        times = 1
+        while times != False and self.scanner.is_open():
+            try:
+                try:
+                    print()
+                except Exception:
+                    print()
+
+                out = 0
+                count = 1
+                if out == 1:
+                    break
+                elif out == 2:
+                    count += 1
+                    if times == 3:
+                        self.func.emit({})
+                        break
+                    else:
+                        continue
+                if out == 3 or out == b"":
+                    if self.times == 3:
+                        break
+                    count += 1
+                    if count == 3:
+                        count = 0
+                        if out == 4:
+                            self.func.emit(ERRPR_CODE_DEFINE.ReceiedError())
+                        else:
+                            print()
+                        break
+                    continue
+                else:
+                    count = 0
+            except Exception:
+                print("upper exception")
+    else:
+        try:
+            print("jump forward")
+            while True:
+                out = self.func.read(count)
+                if out == b"":
+                    self.func.emit(ERRPR_CODE_DEFINE.ReceiedError())
+                    break
+                    continue
+                imagedata = out[0]
+                if imagedata == b"\x05":
+                    self.func.emit(INFORMATION.UnsupportedImage())
+                    break
+                    continue
+                if imagedata == b"\x15":
+                    self.func.emit(INFORMATION.NoneImage())
+                    break
+                    continue
+                if out[1] == False:
+                    start_index = imagedata.find(b"BM6")
+                    self.func.emit(imagedata[start_index:], False)
+                    continue
+                (imagedata, all_code) = imagedata
+                self.func.emit({})
+                self.func.emit({})
+                self.func.emit({})  # remove {} and this works
+                break
+        except Exception:
+            pass
diff --git a/uncompyle6/parsers/parse36.py b/uncompyle6/parsers/parse36.py
index a76a3749..09980695 100644
--- a/uncompyle6/parsers/parse36.py
+++ b/uncompyle6/parsers/parse36.py
@@ -53,6 +53,8 @@ class Python36Parser(Python35Parser):
         for_block       ::= l_stmts_opt come_from_loops JUMP_BACK
         come_from_loops ::= COME_FROM_LOOP*
 
+        whilestmt       ::= SETUP_LOOP testexpr l_stmts_opt
+                            JUMP_BACK come_froms POP_BLOCK
         whilestmt       ::= SETUP_LOOP testexpr l_stmts_opt
                             JUMP_BACK come_froms POP_BLOCK COME_FROM_LOOP
         whilestmt       ::= SETUP_LOOP testexpr l_stmts_opt