diff --git a/sanitiser/_geo.js b/sanitiser/_geo.js
index 517f1c24..14875668 100644
--- a/sanitiser/_geo.js
+++ b/sanitiser/_geo.js
@@ -1,10 +1,11 @@
 var isObject = require('is-object');
 
+
 // validate inputs, convert types and apply defaults
-function sanitize( req, latlon_is_required ){
-  
+module.exports = function sanitize( req, latlon_is_required ){
+
   var clean = req.clean || {};
-  var params= req.query;
+  var params = req.query;
   latlon_is_required = latlon_is_required || false;
 
   // ensure the input params are a valid object
@@ -12,87 +13,102 @@ function sanitize( req, latlon_is_required ){
     params = {};
   }
 
-  var is_invalid_lat = function(lat) {
-    return isNaN( lat ) || lat < -90 || lat > 90;
-  };
-
-  var is_invalid_lon = function(lon) {
-    return isNaN( lon ) || lon < -180 || lon > 180;
-  };
-
-  // lat
-  var lat = parseFloat( params.lat, 10 );
-  if (!isNaN(lat)) {
-    if( is_invalid_lat(lat) ){
-      return {
-        'error': true,
-        'message': 'invalid param \'lat\': must be >-90 and <90'
-      };
-    }
-    clean.lat = lat;
-  } else if (latlon_is_required) {
+  try {
+    sanitize_coord( 'lat', clean, params.lat, latlon_is_required );
+    sanitize_coord( 'lon', clean, params.lon, latlon_is_required );
+    sanitize_zoom_level(clean, params.zoom);
+    sanitize_bbox(clean, params.bbox);
+  }
+  catch (err) {
     return {
       'error': true,
-      'message': 'missing param \'lat\': must be >-90 and <90'
+      'message': err.message
     };
   }
 
-  // lon
-  var lon = parseFloat( params.lon, 10 );
-  if (!isNaN(lon)) {
-    if( is_invalid_lon(lon) ){
-      return {
-        'error': true,
-        'message': 'invalid param \'lon\': must be >-180 and <180'
+  req.clean = clean;
+
+  return { 'error': false };
+};
+
+
+/**
+ * Parse and validate bbox parameter
+ * bbox = bottom_left lat, bottom_left lon, top_right lat, top_right lon
+ * bbox = left,bottom,right,top
+ * bbox = min Longitude , min Latitude , max Longitude , max Latitude
+ *
+ * @param {object} clean
+ * @param {string} param
+ */
+function sanitize_bbox( clean, param ) {
+  if( !param ) {
+    return;
+  }
+
+  var bbox = [];
+  var bboxArr = param.split( ',' );
+
+  if( Array.isArray( bboxArr ) && bboxArr.length === 4 ) {
+
+    bbox = bboxArr.filter( function( latlon, index ) {
+      latlon = parseFloat( latlon, 10 );
+      return !(lat_lon_checks[(index % 2 === 0 ? 'lat' : 'lon')].is_invalid( latlon ));
+    });
+
+    if( bbox.length === 4 ) {
+      clean.bbox = {
+        right: Math.max( bbox[0], bbox[2] ),
+        top: Math.max( bbox[1], bbox[3] ),
+        left: Math.min( bbox[0], bbox[2] ),
+        bottom: Math.min( bbox[1], bbox[3] )
       };
+    } else {
+      throw new Error('invalid bbox');
     }
-    clean.lon = lon;
-  } else if (latlon_is_required) {
-    return {
-      'error': true,
-      'message': 'missing param \'lon\': must be >-180 and <180'
-    };
   }
+}
 
-  // zoom level
-  var zoom = parseInt( params.zoom, 10 );
-  if( !isNaN( zoom ) ){
-    clean.zoom = Math.min( Math.max( zoom, 1 ), 18 ); // max
-  } 
-
-  // bbox 
-  // bbox = bottom_left lat, bottom_left lon, top_right lat, top_right lon
-  // bbox = left,bottom,right,top
-  // bbox = min Longitude , min Latitude , max Longitude , max Latitude 
-  if (params.bbox) {
-    var bbox = [];
-    var bboxArr = params.bbox.split(',');
-    if( Array.isArray(bboxArr) && bboxArr.length === 4 ) {
-      bbox = bboxArr.filter(function(latlon, index) {
-        latlon = parseFloat(latlon, 10);
-        return !(index % 2 === 0 ? is_invalid_lat(latlon) : is_invalid_lon(latlon)); 
-      });
-      if (bbox.length === 4) {
-        clean.bbox = {
-          top   : Math.max(bbox[0], bbox[2]),
-          right : Math.max(bbox[1], bbox[3]),
-          bottom: Math.min(bbox[0], bbox[2]),
-          left  : Math.min(bbox[1], bbox[3])
-        };
-      } else {
-        return {
-          'error': true,
-          'message': 'invalid bbox'
-        };
-      }
+/**
+ * Validate lat,lon values
+ *
+ * @param {string} coord lat|lon
+ * @param {object} clean
+ * @param {string} param
+ * @param {bool} latlon_is_required
+ */
+function sanitize_coord( coord, clean, param, latlon_is_required ) {
+  var value = parseFloat( param, 10 );
+  if ( !isNaN( value ) ) {
+    if( lat_lon_checks[coord].is_invalid( value ) ){
+      throw new Error( 'invalid ' + lat_lon_checks[coord].error_msg );
     }
-  } 
-
-  req.clean = clean;
-  
-  return { 'error': false };
+    clean[coord] = value;
+  }
+  else if (latlon_is_required) {
+    throw new Error('missing ' + lat_lon_checks[coord].error_msg);
+  }
+}
 
+function sanitize_zoom_level( clean, param ) {
+  var zoom = parseInt( param, 10 );
+  if( !isNaN( zoom ) ){
+    clean.zoom = Math.min( Math.max( zoom, 1 ), 18 ); // max
+  }
 }
 
-// export function
-module.exports = sanitize;
+var lat_lon_checks = {
+  lat: {
+    is_invalid: function is_invalid_lat(lat) {
+      return isNaN( lat ) || lat < -90 || lat > 90;
+    },
+    error_msg: 'param \'lat\': must be >-90 and <90'
+  },
+  lon: {
+    is_invalid: function is_invalid_lon(lon) {
+      return isNaN(lon) || lon < -180 || lon > 180;
+    },
+    error_msg: 'param \'lon\': must be >-180 and <180'
+  }
+};
+
diff --git a/test/unit/sanitiser/search.js b/test/unit/sanitiser/search.js
index 4e768d61..7d020a4e 100644
--- a/test/unit/sanitiser/search.js
+++ b/test/unit/sanitiser/search.js
@@ -212,10 +212,10 @@ module.exports.tests.sanitize_bbox = function(test, common) {
           return parseInt(i);
         });
         expected.bbox = {
-          top   : Math.max(bboxArray[0], bboxArray[2]),
-          right : Math.max(bboxArray[1], bboxArray[3]),
-          bottom: Math.min(bboxArray[0], bboxArray[2]),
-          left  : Math.min(bboxArray[1], bboxArray[3])
+          right: Math.max(bboxArray[0], bboxArray[2]),
+          top: Math.max(bboxArray[1], bboxArray[3]),
+          left: Math.min(bboxArray[0], bboxArray[2]),
+          bottom: Math.min(bboxArray[1], bboxArray[3])
         };
         t.equal(err, undefined, 'no error');
         t.deepEqual(clean, expected, 'clean set correctly (' + bbox + ')');
diff --git a/test/unit/sanitiser/suggest.js b/test/unit/sanitiser/suggest.js
index 403a432d..929bb541 100644
--- a/test/unit/sanitiser/suggest.js
+++ b/test/unit/sanitiser/suggest.js
@@ -181,10 +181,10 @@ module.exports.tests.sanitize_bbox = function(test, common) {
           return parseInt(i);
         });
         expected.bbox = {
-          top   : Math.max(bboxArray[0], bboxArray[2]),
-          right : Math.max(bboxArray[1], bboxArray[3]),
-          bottom: Math.min(bboxArray[0], bboxArray[2]),
-          left  : Math.min(bboxArray[1], bboxArray[3])
+          right: Math.max(bboxArray[0], bboxArray[2]),
+          top: Math.max(bboxArray[1], bboxArray[3]),
+          left: Math.min(bboxArray[0], bboxArray[2]),
+          bottom: Math.min(bboxArray[1], bboxArray[3])
         };
         t.equal(err, undefined, 'no error');
         t.deepEqual(clean, expected, 'clean set correctly (' + bbox + ')');