diff --git a/browser/sql-parser.js b/browser/sql-parser.js
index 4ebe726..34e224c 100644
--- a/browser/sql-parser.js
+++ b/browser/sql-parser.js
@@ -213,7 +213,7 @@
 
     SUB_SELECT_OP = ['IN', 'NOT IN', 'ANY', 'ALL', 'SOME'];
 
-    SUB_SELECT_UNARY_OP = ['EXISTS'];
+    SUB_SELECT_UNARY_OP = ['EXISTS', 'NOT EXISTS'];
 
     SQL_CONDITIONALS = ['AND', 'OR'];
 
diff --git a/lib/lexer.js b/lib/lexer.js
index 3f0ed9c..b54f8e2 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -208,7 +208,7 @@
 
     SUB_SELECT_OP = ['IN', 'NOT IN', 'ANY', 'ALL', 'SOME'];
 
-    SUB_SELECT_UNARY_OP = ['EXISTS'];
+    SUB_SELECT_UNARY_OP = ['EXISTS', 'NOT EXISTS'];
 
     SQL_CONDITIONALS = ['AND', 'OR'];
 
diff --git a/src/lexer.coffee b/src/lexer.coffee
index 4cb3d8b..8ec5fd1 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -142,7 +142,7 @@ class Lexer
   SQL_SORT_ORDERS     = ['ASC', 'DESC']
   SQL_OPERATORS       = ['=', '!=', '>=', '>', '<=', '<>', '<', 'LIKE', 'IS NOT', 'IS']
   SUB_SELECT_OP       = ['IN', 'NOT IN', 'ANY', 'ALL', 'SOME']
-  SUB_SELECT_UNARY_OP = ['EXISTS']
+  SUB_SELECT_UNARY_OP = ['EXISTS', 'NOT EXISTS']
   SQL_CONDITIONALS    = ['AND', 'OR']
   SQL_BETWEENS        = ['BETWEEN', 'NOT BETWEEN']
   BOOLEAN             = ['TRUE', 'FALSE', 'NULL']
diff --git a/test/grammar.spec.coffee b/test/grammar.spec.coffee
index c681f7c..6ec1c4a 100644
--- a/test/grammar.spec.coffee
+++ b/test/grammar.spec.coffee
@@ -353,6 +353,16 @@ describe "SQL Grammar", ->
         ))
       """
 
+    it "parses an EXISTS clause containing a query", ->
+      parse("""select * from a where not exists (select foo from bar)""").toString().should.eql """
+      SELECT *
+        FROM `a`
+        WHERE (NOT EXISTS (
+          SELECT `foo`
+            FROM `bar`
+        ))
+      """
+
   describe "aliases", ->
     it "parses aliased table names", ->
       parse("""select * from a b""").toString().should.eql """