diff --git a/README.md b/README.md
index f8d10bb..ea757df 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,10 @@ JavaScript validation example (using [tv4 library](https://github.com/geraintluf
     var postSchema = apidocs.getSchema('item');
     var valid = tv4.validate(myPost, postSchema);
 
+Some of our schemas provide user-friendly error messages. To enable them, load the custom error reporter:
+
+    apidocs.enableCustomErrors(tv4);
+
 Blueprints
 ----------
 
diff --git a/index.coffee b/index.coffee
index 9b8d835..d5d1ef6 100644
--- a/index.coffee
+++ b/index.coffee
@@ -1,11 +1,7 @@
-
 yaml = require 'js-yaml'
 path = require 'path'
 fs = require 'fs'
 
-path = require 'path'
-fs = require 'fs'
-
 schemaPath = './schema'
 
 exports.listSchemas = () ->
@@ -25,3 +21,12 @@ exports.getExamples = (name) ->
   filepath = path.join __dirname, './examples', name+'.yml'
   content = fs.readFileSync filepath, { encoding: 'utf-8' }
   return yaml.safeLoad content
+
+exports.enableCustomErrors = (validator) ->
+  unless typeof validator.setErrorReporter is 'function'
+    throw 'Your validator doesn\'t support custom error messages'
+  validator.setErrorReporter (error, data, schema) ->
+    return error.message unless schema.messages
+    lastSchemaPath = error.schemaPath.split('/').pop()
+    return error.message unless schema.messages[lastSchemaPath]
+    schema.messages[lastSchemaPath]
diff --git a/schemata/base.yaml b/schemata/base.yaml
index 5d109f2..143ee4a 100644
--- a/schemata/base.yaml
+++ b/schemata/base.yaml
@@ -9,31 +9,43 @@ definitions:
     pattern: "^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}$"
     example: 01234567-89ab-cdef-0123-456789abcdef
     type: string
+    messages:
+      pattern: 'Must be a properly-formed UUID'
   url:
     description: Unique Resource Locator
     format: uri
     example: http://thegrid.io
     type: string
+    messages:
+      format: 'Must be a properly-formed URL'
   email:
     description: Email address
     format: email
     example: 'info@thegrid.io'
     type: string
+    messages:
+      format: 'Must be a properly-formed email'
   hostname:
     description: Hostname
     format: hostname
     example: 'blog.thegrid.io'
     type: string
+    messages:
+      format: 'Must be a properly-formed hostname'
   hexcolor:
     description: "#RGB color"
     format: rgbhexcolor
     pattern: "^#([a-fA-F0-9]{6}|[a-fA-F0-9]{3})$"
     example: "#aa33cc"
     type: string
+    messages:
+      pattern: 'Must be a RGB hex string'
   site:
     type: string
     example: "the-domains/the-grid"
     pattern: "^[a-z0-9-_\\.]+\/[a-z0-9-_\\.]+$"
+    messages:
+      pattern: 'Must be a valid GitHub repository name'
   sites:
     type: array
     description: Collection of websites associated with the resource
diff --git a/spec/custom-errors.coffee b/spec/custom-errors.coffee
new file mode 100644
index 0000000..18b4901
--- /dev/null
+++ b/spec/custom-errors.coffee
@@ -0,0 +1,33 @@
+tv4 = require 'tv4'
+tv4Formats = require 'tv4-formats'
+lib = require '../index'
+chai = require 'chai' if not chai
+
+describe 'Custom errors', ->
+  schemas = {}
+  validator = null
+  before ->
+    validator = tv4.freshApi()
+    validator.addFormat tv4Formats
+    lib.enableCustomErrors validator
+    lib.listSchemas().forEach (schemaName) ->
+      schema = lib.getSchema schemaName
+      validator.addSchema schema.id, schema
+      schemas[schemaName] = schema
+  after ->
+    validator.dropSchemas()
+    validator.reset()
+
+  describe 'invalid repo name', ->
+    it 'should produce a custom error', (done) ->
+      baseSchema = schemas['base']
+      chai.expect(baseSchema.definitions.site.messages).to.be.an 'object'
+      chai.expect(baseSchema.definitions.site.messages.pattern).to.exist
+      result = validator.validateMultiple
+        name: 'The Grid'
+        repo: 'foo'
+        path: '/foo'
+      , 'site.json'
+      chai.expect(result.valid).to.equal false
+      chai.expect(result.errors[0].message).to.equal baseSchema.definitions.site.messages.pattern
+      done()
diff --git a/spec/schemas.coffee b/spec/schemas.coffee
index 1e00210..2828dd8 100644
--- a/spec/schemas.coffee
+++ b/spec/schemas.coffee
@@ -1,4 +1,3 @@
-
 tv4 = require 'tv4'
 tv4Formats = require 'tv4-formats'
 chai = require 'chai' if not chai
@@ -9,15 +8,16 @@ lib = require '../index'
 
 describe 'Schemas', ->
   schemas = []
+  validator = tv4.freshApi()
   before ->
-    tv4.addFormat tv4Formats
+    validator.addFormat tv4Formats
   after ->
-    tv4.reset()
-    tv4.dropSchemas()
+    validator.reset()
+    validator.dropSchemas()
 
   lib.listSchemas().forEach (schemaName) ->
     schema = lib.getSchema schemaName
-    tv4.addSchema schema.id, schema
+    validator.addSchema schema.id, schema
     schemas.push schema
 
   schemas.forEach (schema) ->
@@ -31,16 +31,16 @@ describe 'Schemas', ->
       cases.forEach (testcase) ->
 
         describe "#{testcase._name}", ->
-          tv4.addSchema schema.id, schema
+          validator.addSchema schema.id, schema
           if testcase._valid
             it "should be valid", ->
-              results = tv4.validateMultiple testcase._data, schema.id
+              results = validator.validateMultiple testcase._data, schema.id
               chai.expect(results.errors).to.eql []
               chai.expect(results.missing).to.eql []
               chai.expect(results.valid).to.equal true
           else
             it "should be invalid", ->
-              results = tv4.validateMultiple testcase._data, schema.id
+              results = validator.validateMultiple testcase._data, schema.id
               chai.expect(results.errors).to.not.eql []
               chai.expect(results.missing).to.eql []
               chai.expect(results.valid).to.equal false
diff --git a/spec/validate-schemas.coffee b/spec/validate-schemas.coffee
index dbd9afe..86bb2c6 100644
--- a/spec/validate-schemas.coffee
+++ b/spec/validate-schemas.coffee
@@ -15,21 +15,22 @@ loadSchema = (filepath) ->
 describe 'Schema meta validation', ->
   schemas = fs.readdirSync path.join __dirname, schemaPath
   schemaNames = []
+  validator = tv4.freshApi()
   before ->
     metaSchema = loadSchema path.join __dirname, 'json-schema.json'
-    tv4.addSchema 'http://json-schema.org/draft-04/schema', metaSchema
+    validator.addSchema 'http://json-schema.org/draft-04/schema', metaSchema
   after ->
-    tv4.reset()
-    tv4.dropSchemas()
+    validator.reset()
+    validator.dropSchemas()
   schemas.forEach (schemaFile) ->
     schema = getSchema schemaFile
-    tv4.addSchema schema.id, schema
+    validator.addSchema schema.id, schema
     schemaNames.push schema
 
   schemaNames.forEach (schema) ->
     describe "#{schema.id} (#{schema.title or schema.description})", ->
       it 'should validate against JSON meta schema', ->
-        result = tv4.validateMultiple schema, 'http://json-schema.org/draft-04/schema'
+        result = validator.validateMultiple schema, 'http://json-schema.org/draft-04/schema'
         chai.expect(result.missing).to.eql []
         chai.expect(result.errors).to.eql []
         chai.expect(result.valid).to.equal true