diff --git a/sanitiser/_warn_quattroshapes.js b/sanitiser/_warn_quattroshapes.js
new file mode 100644
index 00000000..2b887e5f
--- /dev/null
+++ b/sanitiser/_warn_quattroshapes.js
@@ -0,0 +1,25 @@
+var _ = require('lodash');
+
+function setup( paramName, targetMap ) {
+  return function( raw, clean ){
+    return sanitize( raw, clean );
+  };
+}
+
+function sanitize( raw, clean, opts ) {
+  // error & warning messages
+  var messages = { errors: [], warnings: [] };
+
+  if (_.includes(raw.sources, 'quattroshapes') || _.includes(raw.sources, 'qs')) {
+    messages.warnings.push( 'You are using Quattroshapes as a data source in this query. ' +
+     'Quattroshapes will be disabled as a data source for Mapzen Search in the next several ' +
+     'weeks, and is being replaced by Who\'s on First, an actively maintained data project ' +
+     'based on Quattroshapes. Your existing queries WILL CONTINUE TO WORK for the foreseeable ' +
+     'future, but results will be coming from Who\'s on First and `sources=quattroshapes` will ' +
+     'be deprecated. If you have any questions, please email search@mapzen.com.');
+  }
+
+  return messages;
+}
+
+module.exports = setup;
diff --git a/sanitiser/reverse.js b/sanitiser/reverse.js
index 154fd3d9..6ebcfd14 100644
--- a/sanitiser/reverse.js
+++ b/sanitiser/reverse.js
@@ -5,6 +5,7 @@ var sanitizeAll = require('../sanitiser/sanitizeAll'),
       singleScalarParameters: require('../sanitiser/_single_scalar_parameters'),
       layers: require('../sanitiser/_targets')('layers', type_mapping.layer_with_aliases_to_type),
       sources: require('../sanitiser/_targets')('sources', type_mapping.source_to_type),
+      quattroshapes_warning: require('../sanitiser/_warn_quattroshapes')(),
       size: require('../sanitiser/_size'),
       private: require('../sanitiser/_flag_bool')('private', false),
       geo_reverse: require('../sanitiser/_geo_reverse'),
diff --git a/sanitiser/search.js b/sanitiser/search.js
index cc596b26..75be20ca 100644
--- a/sanitiser/search.js
+++ b/sanitiser/search.js
@@ -7,6 +7,7 @@ var sanitizeAll = require('../sanitiser/sanitizeAll'),
       size: require('../sanitiser/_size'),
       layers: require('../sanitiser/_targets')('layers', type_mapping.layer_with_aliases_to_type),
       sources: require('../sanitiser/_targets')('sources', type_mapping.source_to_type),
+      quattroshapes_warning: require('../sanitiser/_warn_quattroshapes')(),
       private: require('../sanitiser/_flag_bool')('private', false),
       geo_search: require('../sanitiser/_geo_search'),
       boundary_country: require('../sanitiser/_boundary_country'),
diff --git a/test/ciao/reverse/sources_layers_invalid_combo.coffee b/test/ciao/reverse/sources_layers_invalid_combo.coffee
index 17de70ca..25ae9da3 100644
--- a/test/ciao/reverse/sources_layers_invalid_combo.coffee
+++ b/test/ciao/reverse/sources_layers_invalid_combo.coffee
@@ -27,7 +27,7 @@ should.exist json.geocoding.errors
 json.geocoding.errors.should.eql [ 'You have specified both the `sources` and `layers` parameters in a combination that will return no results.' ]
 
 #? expected warnings
-should.not.exist json.geocoding.warnings
+json.geocoding.warnings.should.eql [ 'You are using Quattroshapes as a data source in this query. Quattroshapes will be disabled as a data source for Mapzen Search in the next several weeks, and is being replaced by Who\'s on First, an actively maintained data project based on Quattroshapes. Your existing queries WILL CONTINUE TO WORK for the foreseeable future, but results will be coming from Who\'s on First and `sources=quattroshapes` will be deprecated. If you have any questions, please email search@mapzen.com.' ]
 
 #? inputs
 json.geocoding.query['size'].should.eql 10
diff --git a/test/ciao/search/sources_layers_invalid_combo.coffee b/test/ciao/search/sources_layers_invalid_combo.coffee
index c0f84b13..d73ca61a 100644
--- a/test/ciao/search/sources_layers_invalid_combo.coffee
+++ b/test/ciao/search/sources_layers_invalid_combo.coffee
@@ -27,7 +27,7 @@ should.exist json.geocoding.errors
 json.geocoding.errors.should.eql [ 'You have specified both the `sources` and `layers` parameters in a combination that will return no results.' ]
 
 #? expected warnings
-should.not.exist json.geocoding.warnings
+json.geocoding.warnings.should.eql [ 'You are using Quattroshapes as a data source in this query. Quattroshapes will be disabled as a data source for Mapzen Search in the next several weeks, and is being replaced by Who\'s on First, an actively maintained data project based on Quattroshapes. Your existing queries WILL CONTINUE TO WORK for the foreseeable future, but results will be coming from Who\'s on First and `sources=quattroshapes` will be deprecated. If you have any questions, please email search@mapzen.com.' ]
 
 #? inputs
 json.geocoding.query['text'].should.eql 'a'
diff --git a/test/unit/sanitiser/reverse.js b/test/unit/sanitiser/reverse.js
index 4e727b5b..d9fdebc9 100644
--- a/test/unit/sanitiser/reverse.js
+++ b/test/unit/sanitiser/reverse.js
@@ -38,7 +38,8 @@ module.exports.tests.interface = function(test, common) {
 
 module.exports.tests.sanitisers = function(test, common) {
   test('check sanitiser list', function (t) {
-    var expected = ['singleScalarParameters', 'layers', 'sources', 'size', 'private', 'geo_reverse', 'boundary_country'];
+    var expected = [ 'singleScalarParameters', 'layers', 'sources', 'quattroshapes_warning',
+      'size', 'private', 'geo_reverse', 'boundary_country' ];
     t.deepEqual(Object.keys(reverse.sanitiser_list), expected);
     t.end();
   });
diff --git a/test/unit/sanitiser/search.js b/test/unit/sanitiser/search.js
index b00160dd..07178626 100644
--- a/test/unit/sanitiser/search.js
+++ b/test/unit/sanitiser/search.js
@@ -24,7 +24,8 @@ module.exports.tests.interface = function(test, common) {
 
 module.exports.tests.sanitisers = function(test, common) {
   test('check sanitiser list', function (t) {
-    var expected = ['singleScalarParameters', 'text', 'size', 'layers', 'sources', 'private', 'geo_search', 'boundary_country' ];
+    var expected = [ 'singleScalarParameters', 'text', 'size', 'layers', 'sources',
+      'quattroshapes_warning', 'private', 'geo_search', 'boundary_country' ];
     t.deepEqual(Object.keys(search.sanitiser_list), expected);
     t.end();
   });