diff --git a/sqlparse/keywords.py b/sqlparse/keywords.py
index 9c37e502..1b63939a 100644
--- a/sqlparse/keywords.py
+++ b/sqlparse/keywords.py
@@ -45,7 +45,7 @@ def is_keyword(value):
         (r'(?<!\w)[$:?]\w+', tokens.Name.Placeholder),
 
         (r'\\\w+', tokens.Command),
-
+        (r'(NOT\s+)?(IN)\b', tokens.Operator.Comparison),
         # FIXME(andi): VALUES shouldn't be listed here
         # see https://github.com/andialbrecht/sqlparse/pull/64
         # AS and IN are special, it may be followed by a parenthesis, but
diff --git a/tests/test_grouping.py b/tests/test_grouping.py
index 87dcf117..253d1ef5 100644
--- a/tests/test_grouping.py
+++ b/tests/test_grouping.py
@@ -373,10 +373,20 @@ def test_grouping_function_not_in():
     # issue183
     p = sqlparse.parse('in(1, 2)')[0]
     assert len(p.tokens) == 2
-    assert p.tokens[0].ttype == T.Keyword
+    assert p.tokens[0].ttype == T.Comparison
     assert isinstance(p.tokens[1], sql.Parenthesis)
 
 
+def test_in_comparison():
+    # issue566
+    p = sqlparse.parse('a in (1, 2)')[0]
+    assert len(p.tokens) == 1
+    assert isinstance(p.tokens[0], sql.Comparison)
+    assert len(p.tokens[0].tokens) == 5
+    assert p.tokens[0].left.value == 'a'
+    assert p.tokens[0].right.value == '(1, 2)'
+
+
 def test_grouping_varchar():
     p = sqlparse.parse('"text" Varchar(50) NOT NULL')[0]
     assert isinstance(p.tokens[2], sql.Function)