diff --git a/lib/dot/definitions.def b/lib/dot/definitions.def
index 76150ce..bde38fb 100644
--- a/lib/dot/definitions.def
+++ b/lib/dot/definitions.def
@@ -3,7 +3,7 @@
     var $lvl = it.level;
     var $dataLvl = it.dataLevel;
     var $schema = it.schema[$keyword];
-    var $schemaPath = it.schemaPath + '.' + $keyword;
+    var $schemaPath = it.schemaPath + '[\'' + $keyword + '\']';
     var $errSchemaPath = it.errSchemaPath + '/' + $keyword;
     var $breakOnError = !it.opts.allErrors;
     var $errorKeyword;
diff --git a/lib/keyword.js b/lib/keyword.js
index 954baca..a34774e 100644
--- a/lib/keyword.js
+++ b/lib/keyword.js
@@ -1,6 +1,6 @@
 'use strict';
 
-var IDENTIFIER = /^[a-z_$][a-z0-9_$]*$/i;
+var IDENTIFIER = /^.*$/i;
 var customRuleCode = require('./dotjs/custom');
 
 module.exports = {
diff --git a/spec/custom.spec.js b/spec/custom.spec.js
index 6150222..7a68650 100644
--- a/spec/custom.spec.js
+++ b/spec/custom.spec.js
@@ -37,7 +37,7 @@ describe('Custom keywords', function () {
           metaSchema: { "type": "boolean" }
         });
 
-        shouldBeInvalidSchema({ "even": "not_boolean" });
+        shouldBeInvalidSchema({ "x-even": "not_boolean" });
 
         function validateEven(schema, data) {
           return data % 2 ? !schema : schema;
@@ -69,9 +69,9 @@ describe('Custom keywords', function () {
             "additionalItems": false
           }
         });
-        shouldBeInvalidSchema({ range: [ "1", 2 ] });
-        shouldBeInvalidSchema({ range: {} });
-        shouldBeInvalidSchema({ range: [ 1, 2, 3 ] });
+        shouldBeInvalidSchema({ 'x-range': [ "1", 2 ] });
+        shouldBeInvalidSchema({ 'x-range': {} });
+        shouldBeInvalidSchema({ 'x-range': [ 1, 2, 3 ] });
 
         function validateRange(schema, data, parentSchema) {
           return parentSchema.exclusiveRange === true
@@ -94,7 +94,7 @@ describe('Custom keywords', function () {
           var valid = minOk && maxOk;
 
           if (!valid) {
-            var err = { keyword: 'range' };
+            var err = { keyword: 'x-range' };
             validateRange.errors = [err];
             var comparison, limit;
             if (minOk) {
@@ -121,7 +121,7 @@ describe('Custom keywords', function () {
     describe('rule with "compiled" keyword validation', function() {
       it('should add and validate rule', function() {
         testEvenKeyword({ type: 'number', compile: compileEven });
-        shouldBeInvalidSchema({ "even": "not_boolean" });
+        shouldBeInvalidSchema({ "x-even": "not_boolean" });
 
         function compileEven(schema) {
           if (typeof schema != 'boolean') throw new Error('The value of "even" keyword must be boolean');
@@ -138,7 +138,7 @@ describe('Custom keywords', function () {
           compile: compileEven,
           metaSchema: { "type": "boolean" }
         });
-        shouldBeInvalidSchema({ "even": "not_boolean" });
+        shouldBeInvalidSchema({ "x-even": "not_boolean" });
 
         function compileEven(schema) {
           return schema ? isEven : isOdd;
@@ -565,7 +565,7 @@ describe('Custom keywords', function () {
         metaSchema: { "type": "boolean" }
       });
       compileCalled .should.equal(true);
-      shouldBeInvalidSchema({ "even": "false" });
+      shouldBeInvalidSchema({ "x-even-$data": "false" });
 
       function validateEven(schema, data) {
         return data % 2 ? !schema : schema;
@@ -613,7 +613,7 @@ describe('Custom keywords', function () {
         metaSchema: { "type": "boolean" }
       }, 2);
       macroCalled .should.equal(true);
-      shouldBeInvalidSchema({ "even": "false" });
+      shouldBeInvalidSchema({ "x-even-$data": "false" });
 
       function validateEven(schema, data) {
         return data % 2 ? !schema : schema;
@@ -658,7 +658,7 @@ describe('Custom keywords', function () {
         metaSchema: { "type": "boolean" }
       });
       inlineCalled .should.equal(true);
-      shouldBeInvalidSchema({ "even": "false" });
+      shouldBeInvalidSchema({ "x-even-$data": "false" });
 
       function validateEven(schema, data) {
         return data % 2 ? !schema : schema;
@@ -685,8 +685,8 @@ describe('Custom keywords', function () {
 
   function testEvenKeyword(definition, numErrors) {
     instances.forEach(function (_ajv) {
-      _ajv.addKeyword('even', definition);
-      var schema = { "even": true };
+      _ajv.addKeyword('x-even', definition);
+      var schema = { "x-even": true };
       var validate = _ajv.compile(schema);
 
       shouldBeValid(validate, 2);
@@ -698,9 +698,9 @@ describe('Custom keywords', function () {
 
   function testEvenKeyword$data(definition, numErrors) {
     instances.forEach(function (_ajv) {
-      _ajv.addKeyword('even', definition);
+      _ajv.addKeyword('x-even-$data', definition);
 
-      var schema = { "even": true };
+      var schema = { "x-even-$data": true };
       var validate = _ajv.compile(schema);
 
       shouldBeValid(validate, 2);
@@ -710,7 +710,7 @@ describe('Custom keywords', function () {
 
       schema = {
         "properties": {
-          "data": { "even": { "$data": "1/evenValue" } },
+          "data": { "x-even-$data": { "$data": "1/evenValue" } },
           "evenValue": {}
         }
       };
@@ -744,15 +744,15 @@ describe('Custom keywords', function () {
 
   function testMultipleConstantKeyword(definition, numErrors) {
     instances.forEach(function (_ajv) {
-      _ajv.addKeyword('constant', definition);
+      _ajv.addKeyword('x-constant', definition);
 
       var schema = {
         "properties": {
-          "a": { "constant": 1 },
-          "b": { "constant": 1 }
+          "a": { "x-constant": 1 },
+          "b": { "x-constant": 1 }
         },
-        "additionalProperties": { "constant": { "foo": "bar" } },
-        "items": { "constant": { "foo": "bar" } }
+        "additionalProperties": { "x-constant": { "foo": "bar" } },
+        "items": { "x-constant": { "foo": "bar" } }
       };
       var validate = _ajv.compile(schema);
 
@@ -771,9 +771,9 @@ describe('Custom keywords', function () {
 
   function testRangeKeyword(definition, customErrors, numErrors) {
     instances.forEach(function (_ajv) {
-      _ajv.addKeyword('range', definition);
+      _ajv.addKeyword('x-range', definition);
 
-      var schema = { "range": [2, 4] };
+      var schema = { "x-range": [2, 4] };
       var validate = _ajv.compile(schema);
 
       shouldBeValid(validate, 2);
@@ -782,14 +782,14 @@ describe('Custom keywords', function () {
       shouldBeValid(validate, 'abc');
 
       shouldBeInvalid(validate, 1.99, numErrors);
-      if (customErrors) shouldBeRangeError(validate.errors[0], '', '#/range', '>=', 2);
+      if (customErrors) shouldBeRangeError(validate.errors[0], '', '#/x-range', '>=', 2);
       shouldBeInvalid(validate, 4.01, numErrors);
-      if (customErrors) shouldBeRangeError(validate.errors[0], '', '#/range','<=', 4);
+      if (customErrors) shouldBeRangeError(validate.errors[0], '', '#/x-range','<=', 4);
 
       schema = {
         "properties": {
           "foo": {
-            "range": [2, 4],
+            "x-range": [2, 4],
             "exclusiveRange": true
           }
         }
@@ -801,23 +801,23 @@ describe('Custom keywords', function () {
       shouldBeValid(validate, { foo: 3.99 });
 
       shouldBeInvalid(validate, { foo: 2 }, numErrors);
-      if (customErrors) shouldBeRangeError(validate.errors[0], '.foo', '#/properties/foo/range', '>', 2, true);
+      if (customErrors) shouldBeRangeError(validate.errors[0], '.foo', '#/properties/foo/x-range', '>', 2, true);
       shouldBeInvalid(validate, { foo: 4 }, numErrors);
-      if (customErrors) shouldBeRangeError(validate.errors[0], '.foo', '#/properties/foo/range', '<', 4, true);
+      if (customErrors) shouldBeRangeError(validate.errors[0], '.foo', '#/properties/foo/x-range', '<', 4, true);
     });
   }
 
   function testMultipleRangeKeyword(definition, numErrors) {
     instances.forEach(function (_ajv) {
-      _ajv.addKeyword('range', definition);
+      _ajv.addKeyword('x-range', definition);
 
       var schema = {
         "properties": {
-          "a": { "range": [2, 4], "exclusiveRange": true },
-          "b": { "range": [2, 4], "exclusiveRange": false }
+          "a": { "x-range": [2, 4], "exclusiveRange": true },
+          "b": { "x-range": [2, 4], "exclusiveRange": false }
         },
-        "additionalProperties": { "range": [5, 7] },
-        "items": { "range": [5, 7] }
+        "additionalProperties": { "x-range": [5, 7] },
+        "items": { "x-range": [5, 7] }
       };
       var validate = _ajv.compile(schema);
 
@@ -836,7 +836,7 @@ describe('Custom keywords', function () {
     delete error.schema;
     delete error.data;
     error .should.eql({
-      keyword: 'range',
+      keyword: 'x-range',
       dataPath: dataPath,
       schemaPath: schemaPath,
       message: 'should be ' + comparison + ' ' + limit,
@@ -906,14 +906,14 @@ describe('Custom keywords', function () {
       }
     });
 
-    it('should throw if keyword is not a valid identifier', function() {
+    it('should not throw even if keyword is not a valid identifier', function() {
       should.not.throw(function() {
         ajv.addKeyword('mykeyword', {
           validate: function() { return true; }
         });
       });
 
-      should.throw(function() {
+      should.not.throw(function() {
         ajv.addKeyword('my-keyword', {
           validate: function() { return true; }
         });
diff --git a/spec/custom_rules/range.jst b/spec/custom_rules/range.jst
index 74f5686..adb481e 100644
--- a/spec/custom_rules/range.jst
+++ b/spec/custom_rules/range.jst
@@ -1,7 +1,7 @@
 {{
   var $data = 'data' + (it.dataLevel || '')
-    , $min = it.schema.range[0]
-    , $max = it.schema.range[1]
+    , $min = it.schema['x-range'][0]
+    , $max = it.schema['x-range'][1]
     , $gt = it.schema.exclusiveRange ? '>' : '>='
     , $lt = it.schema.exclusiveRange ? '<' : '<=';
 }}
diff --git a/spec/custom_rules/range_with_errors.jst b/spec/custom_rules/range_with_errors.jst
index a9bb7da..6bfb6e5 100644
--- a/spec/custom_rules/range_with_errors.jst
+++ b/spec/custom_rules/range_with_errors.jst
@@ -1,7 +1,7 @@
 {{
   var $data = 'data' + (it.dataLevel || '')
-    , $min = it.schema.range[0]
-    , $max = it.schema.range[1]
+    , $min = it.schema['x-range'][0]
+    , $max = it.schema['x-range'][1]
     , $exclusive = !!it.schema.exclusiveRange
     , $gt = $exclusive ? '>' : '>='
     , $lt = $exclusive ? '<' : '<='
@@ -16,7 +16,7 @@ if (!valid{{=$lvl}}) {
   var {{=$err}};
   if (minOk{{=$lvl}}) {
     {{=$err}} = {
-      keyword: 'range',
+      keyword: 'x-range',
       message: 'should be {{=$lt}} {{=$max}}',
       params: {
         comparison: '{{=$lt}}',
@@ -26,7 +26,7 @@ if (!valid{{=$lvl}}) {
     };
   } else {
     {{=$err}} = {
-      keyword: 'range',
+      keyword: 'x-range',
       message: 'should be {{=$gt}} {{=$min}}',
       params: {
         comparison: '{{=$gt}}',