diff --git a/README.md b/README.md
index 2eee7ff53..61fb0c061 100644
--- a/README.md
+++ b/README.md
@@ -51,8 +51,8 @@ Documentation: <https://shopify.github.io/liquid/basics/introduction/#filters>
 - [x] default [Document](https://shopify.github.io/liquid/filters/default) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
 - [x] divided_by [Document](https://shopify.github.io/liquid/filters/divided_by) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
 - [x] downcase [Document](https://shopify.github.io/liquid/filters/downcase) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
-- [ ] escape [Document](https://shopify.github.io/liquid/filters/escape) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
-- [ ] escape_once [Document](https://shopify.github.io/liquid/filters/escape_once) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
+- [x] escape [Document](https://shopify.github.io/liquid/filters/escape) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
+- [x] escape_once [Document](https://shopify.github.io/liquid/filters/escape_once) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
 - [ ] first [Document](https://shopify.github.io/liquid/filters/first) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
 - [ ] floor [Document](https://shopify.github.io/liquid/filters/floor) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
 - [ ] join [Document](https://shopify.github.io/liquid/filters/join) [Source](https://github.com/harttle/shopify-liquid/blob/master/filters.js) [Test][ft]
diff --git a/filters.js b/filters.js
index 361dfbb7e..0b383490e 100644
--- a/filters.js
+++ b/filters.js
@@ -10,4 +10,6 @@ module.exports = function(liquid) {
     liquid.registerFilter('default', (v, arg) => arg || v);
     liquid.registerFilter('divided_by', (v, arg) => Math.floor(v/arg));
     liquid.registerFilter('downcase', v => v.toLowerCase());
+    liquid.registerFilter('escape', v => _.escape(v));
+    liquid.registerFilter('escape_once', v => _.escape(_.unescape(v)));
 };
diff --git a/scope.js b/scope.js
index 0d2ce73ea..49f17155d 100644
--- a/scope.js
+++ b/scope.js
@@ -1,5 +1,6 @@
 const _ = require('lodash');
 const lexical = require('./lexical.js');
+const error = require('./error.js');
 
 var scope = {
     get: function(str) {
@@ -23,6 +24,7 @@ var scope = {
         return this;
     },
     push: function(ctx) {
+        if(!ctx) error(`trying to push ${ctx} into scopes`);
         return this.scopes.push(ctx);
     },
     pop: function() {
@@ -32,6 +34,6 @@ var scope = {
 
 exports.factory = function(_ctx) {
     var ctx = Object.create(scope);
-    ctx.scopes = [_ctx];
+    ctx.scopes = _ctx ? [_ctx] : [];
     return ctx;
 };
diff --git a/test/filters.js b/test/filters.js
index 7bdf9d901..1c1b183f9 100644
--- a/test/filters.js
+++ b/test/filters.js
@@ -1,53 +1,66 @@
 const chai = require("chai");
 const expect = chai.expect;
 
-var liquid = require('..')();
+var liquid = require('..')(), ctx;
 
-describe('filters', function() {
-    var ctx = {
+function test(src, dst) {
+    ctx = {
+        date: new Date(),
         foo: 'bar',
         arr: [-2, 'a']
     };
+    expect(liquid.render(src, ctx)).to.equal(dst);
+}
 
+describe('filters', function() {
     it('should support abs', function() {
-        expect(liquid.render('{{ -3 | abs }}')).to.equal('3');
-        expect(liquid.render('{{ arr[0] | abs }}', ctx)).to.equal('2');
+        test('{{ -3 | abs }}', '3');
+        test('{{ arr[0] | abs }}', '2');
     });
 
     it('should support append', function() {
-        expect(liquid.render('{{ -3 | append: "abc" }}')).to.equal('-3abc');
-        expect(liquid.render('{{ "a" | append: foo }}', ctx)).to.equal('abar');
+        test('{{ -3 | append: "abc" }}', '-3abc');
+        test('{{ "a" | append: foo }}', 'abar');
     });
 
     it('should support capitalize', function() {
-        expect(liquid.render('{{ "i am good" | capitalize }}')).to.equal('I am good');
+        test('{{ "i am good" | capitalize }}', 'I am good');
     });
 
     it('should support ceil', function() {
-        expect(liquid.render('{{ 1.2 | ceil }}')).to.equal('2');
-        expect(liquid.render('{{ 2.0 | ceil }}')).to.equal('2');
-        expect(liquid.render('{{ "3.5" | ceil }}')).to.equal('4');
-        expect(liquid.render('{{ 183.357 | ceil }}')).to.equal('184');
+        test('{{ 1.2 | ceil }}', '2');
+        test('{{ 2.0 | ceil }}', '2');
+        test('{{ "3.5" | ceil }}', '4');
+        test('{{ 183.357 | ceil }}', '184');
     });
 
     it('should support date', function() {
-        var d = ctx.date = new Date();
-        str = d.toDateString();
-        expect(liquid.render('{{ date | date:"%a %b %d %Y"}}', ctx)).to.equal(str);
+        str = ctx.date.toDateString();
+        test('{{ date | date:"%a %b %d %Y"}}', str);
     });
 
     it('should support default', function() {
-        expect(liquid.render('{{false |default: "a"}}')).to.equal('a');
+        test('{{false |default: "a"}}', 'a');
     });
 
     it('should support divided_by', function() {
-        expect(liquid.render('{{4 | divided_by: 2}}')).to.equal('2');
-        expect(liquid.render('{{16 | divided_by: 4}}')).to.equal('4');
-        expect(liquid.render('{{5 | divided_by: 3}}')).to.equal('1');
+        test('{{4 | divided_by: 2}}', '2');
+        test('{{16 | divided_by: 4}}', '4');
+        test('{{5 | divided_by: 3}}', '1');
     });
 
     it('should support downcase', function() {
-        expect(liquid.render('{{ "Parker Moore" | downcase }}')).to.equal('parker moore');
-        expect(liquid.render('{{ "apple" | downcase }}')).to.equal('apple');
+        test('{{ "Parker Moore" | downcase }}', 'parker moore');
+        test('{{ "apple" | downcase }}', 'apple');
+    });
+    it('should support escape', function() {
+        test('{{ "Have you read \'James & the Giant Peach\'?" | escape }}',
+            'Have you read &#39;James &amp; the Giant Peach&#39;?');
+        test('{{ "Tetsuro Takara" | escape }}', 'Tetsuro Takara');
+    });
+    it('should support escape_once', function() {
+        test('{{ "1 < 2 & 3" | escape_once }}', '1 &lt; 2 &amp; 3');
+        test('{{ "1 &lt; 2 &amp; 3" | escape_once }}', '1 &lt; 2 &amp; 3');
     });
 });
+
diff --git a/test/tags.js b/test/tags.js
index 111cd8e8d..39e86b5ff 100644
--- a/test/tags.js
+++ b/test/tags.js
@@ -4,6 +4,16 @@ const expect = chai.expect;
 var liquid = require('..')(),
     ctx;
 
+function test(src, dst) {
+    expect(liquid.render(src, ctx)).to.equal(dst);
+}
+
+function testThrow (src, pattern) {
+    expect(function() {
+        liquid.render(src, ctx);
+    }).to.throw(pattern);
+}
+
 describe('tags', function() {
     beforeEach(function() {
         ctx = {
@@ -16,51 +26,47 @@ describe('tags', function() {
         };
     });
     it('should support assign', function() {
-        expect(liquid.render('{% assign foo="bar"%}{{foo}}', ctx)).to.equal('bar');
+        test('{% assign foo="bar"%}{{foo}}', 'bar');
     });
     it('should support case', function() {
-        expect(function() {
-            liquid.render('{% case "foo"%}');
-        }).to.throw(/case "foo" not closed/);
-        expect(liquid.render('{% case "foo"%}' +
+        testThrow('{% case "foo"%}', /case "foo" not closed/);
+        test('{% case "foo"%}' +
             '{% when "foo" %}foo{% when "bar"%}bar' +
-            '{%endcase%}', ctx)).to.equal('foo');
-        expect(liquid.render('{% case empty %}' +
+            '{%endcase%}', 'foo');
+        test('{% case empty %}' +
             '{% when "foo" %}foo{% when ""%}bar' +
-            '{%endcase%}')).to.equal('bar');
-        expect(liquid.render('{% case false %}' +
+            '{%endcase%}', 'bar');
+        test('{% case false %}' +
             '{% when "foo" %}foo{% when ""%}bar' +
-            '{%endcase%}')).to.equal('');
-        expect(liquid.render('{% case "a" %}' +
+            '{%endcase%}', '');
+        test('{% case "a" %}' +
             '{% when "b" %}b{% when "c"%}c{%else %}d' +
-            '{%endcase%}')).to.equal('d');
+            '{%endcase%}', 'd');
     });
 
     it('should support if', function() {
-        expect(liquid.render('{% if 2==3 %}yes{%else%}no{%endif%}', ctx)).to.equal('no');
-        expect(liquid.render('{% if 1==2 and one<two %}a{%endif%}', ctx)).to.equal('');
-        expect(liquid.render('{% if false %}yes{%else%}no{%endif%}', ctx)).to.equal('no');
+        test('{% if 2==3 %}yes{%else%}no{%endif%}', 'no');
+        test('{% if 1==2 and one<two %}a{%endif%}', '');
+        test('{% if false %}yes{%else%}no{%endif%}', 'no');
     });
 
     it('should support unless', function() {
-        expect(liquid.render('{% unless 1 %}yes{%else%}no{%endunless%}', ctx)).to.equal('no');
-        expect(liquid.render('{% unless 1>2 %}yes{%endunless%}', ctx)).to.equal('yes');
+        test('{% unless 1 %}yes{%else%}no{%endunless%}', 'no');
+        test('{% unless 1>2 %}yes{%endunless%}', 'yes');
     });
 
     it('should support capture', function() {
-        expect(liquid.render('{% capture f %}{{"a" | capitalize}}{%endcapture%}{{f}}', ctx)).to.equal('A');
-        expect(function() {
-            liquid.render('{% capture = %}{%endcapture%}', ctx);
-        }).to.throw(/= not valid identifier/);
+        test('{% capture f %}{{"a" | capitalize}}{%endcapture%}{{f}}', 'A');
+        testThrow('{% capture = %}{%endcapture%}', /= not valid identifier/);
     });
 
     it('should support increment', function() {
-        expect(liquid.render('{% increment foo %}{%increment foo%}{{foo}}', ctx)).to.equal('2');
-        expect(liquid.render('{% increment one %}{{one}}', ctx)).to.equal('2');
+        test('{% increment foo %}{%increment foo%}{{foo}}', '2');
+        test('{% increment one %}{{one}}', '2');
     });
 
     it('should support decrement', function() {
-        expect(liquid.render('{% decrement foo %}{%decrement foo%}{{foo}}', ctx)).to.equal('-2');
-        expect(liquid.render('{% decrement one %}{{one}}', ctx)).to.equal('0');
+        test('{% decrement foo %}{%decrement foo%}{{foo}}', '-2');
+        test('{% decrement one %}{{one}}', '0');
     });
 });