diff --git a/test/jstests/operators.py b/test/jstests/operators.py
index c95a8baca..c70bac39b 100644
--- a/test/jstests/operators.py
+++ b/test/jstests/operators.py
@@ -39,5 +39,16 @@ tests = [
                      (Token.OP, _OPERATORS['>>'][1])
                  ]), None)
              ]))]
+    }, {
+        'code': 'return -5 + +3;',
+        'asserts': [{'value': -2}]
+    }, {
+        'code': 'return -5 + ++a;',
+        'globals': {'a': -3},
+        'asserts': [{'value': -7}]
+    }, {
+        'code': 'function f() {return -5 + a++;}',
+        'globals': {'a': -3},
+        'asserts': [{'value': -8, 'call': ('f',)}, {'value': -7, 'call': ('f',)}]
     }
 ]
diff --git a/youtube_dl/jsinterp/jsinterp.py b/youtube_dl/jsinterp/jsinterp.py
index 0232f8d20..0fbb734d5 100644
--- a/youtube_dl/jsinterp/jsinterp.py
+++ b/youtube_dl/jsinterp/jsinterp.py
@@ -3,7 +3,7 @@ from __future__ import unicode_literals
 import re
 
 from ..utils import ExtractorError
-from .tstream import TokenStream, _UNARY_OPERATORS
+from .tstream import TokenStream, convert_to_unary
 from .jsgrammar import Token, token_keys
 
 
@@ -744,7 +744,7 @@ class JSInterpreter(object):
                 if peek_id is Token.OP and peek_value[0] in (Token.ADD, Token.SUB):
                     # any binary operators will be consumed later
                     peek_id = Token.UOP
-                    peek_value = {Token.ADD: _UNARY_OPERATORS['+'], Token.SUB: _UNARY_OPERATORS['-']}[peek_value[0]]
+                    peek_value = convert_to_unary(peek_value)
                 if peek_id is Token.UOP:
                     name, op = peek_value
                     had_inc = name in (Token.INC, Token.DEC)
@@ -881,17 +881,18 @@ class JSInterpreter(object):
         elif name is Token.OPEXPR:
             stack = []
             rpn = expr[1][:]
+            # FIXME support pre- and postfix operators
             while rpn:
                 token = rpn.pop(0)
-                # XXX add unary operator 'delete', 'void', 'instanceof'
                 # XXX relation 'in' 'instanceof'
-                if token[0] in (Token.OP, Token.AOP, Token.UOP, Token.LOP, Token.REL):
+                if token[0] in (Token.OP, Token.AOP, Token.LOP, Token.REL):
                     right = stack.pop()
                     left = stack.pop()
                     stack.append(Reference(token[1](left.getvalue(), right.getvalue())))
+                # XXX add unary operator 'delete', 'void', 'instanceof'
                 elif token[0] is Token.UOP:
                     right = stack.pop()
-                    stack.append(token[1](right.getvalue()))
+                    stack.append(Reference(token[1](right.getvalue())))
                 else:
                     stack.append(self.interpret_expression(token))
             result = stack.pop()
diff --git a/youtube_dl/jsinterp/tstream.py b/youtube_dl/jsinterp/tstream.py
index e4786b5ed..8a37b53c2 100644
--- a/youtube_dl/jsinterp/tstream.py
+++ b/youtube_dl/jsinterp/tstream.py
@@ -13,8 +13,7 @@ from .jsgrammar import (
     RELATIONS_RE,
     ASSIGN_OPERATORS_RE,
     OPERATORS_RE,
-    Token,
-    token_keys
+    Token
 )
 
 _PUNCTUATIONS = {
@@ -40,7 +39,7 @@ _UNARY_OPERATORS = {
     '++': (Token.INC, lambda cur: cur + 1),
     '--': (Token.DEC, lambda cur: cur - 1),
     '!': (Token.NOT, operator.not_),
-    '~': (Token.BNOT, operator.invert),
+    '~': (Token.BNOT, operator.inv),
     # XXX define these operators
     'delete': (Token.DEL, None),
     'void': (Token.VOID, None),
@@ -99,6 +98,10 @@ _input_element = re.compile(r'\s*(?:%(comment)s|%(token)s|%(lop)s|%(uop)s|%(aop)
 })
 
 
+def convert_to_unary(token_value):
+    return {Token.ADD: _UNARY_OPERATORS['+'], Token.SUB: _UNARY_OPERATORS['-']}[token_value[0]]
+
+
 class TokenStream(object):
     def __init__(self, code, start=0):
         self.code = code