diff --git a/src/SearchParameters/RefinementList.js b/src/SearchParameters/RefinementList.js
index c44002dd9..9c39f3557 100644
--- a/src/SearchParameters/RefinementList.js
+++ b/src/SearchParameters/RefinementList.js
@@ -15,8 +15,8 @@
 var isUndefined = require('lodash/isUndefined');
 var isFunction = require('lodash/isFunction');
 var isEmpty = require('lodash/isEmpty');
-var defaults = require('lodash/defaults');
 
+var defaultsPure = require('../functions/defaultsPure');
 var omit = require('../functions/omit');
 
 var lib = {
@@ -42,7 +42,7 @@ var lib = {
 
     mod[attribute] = facetRefinement;
 
-    return defaults({}, mod, refinementList);
+    return defaultsPure({}, mod, refinementList);
   },
   /**
    * Removes refinement(s) for an attribute:
diff --git a/src/SearchParameters/index.js b/src/SearchParameters/index.js
index ad42c819c..c46b9915c 100644
--- a/src/SearchParameters/index.js
+++ b/src/SearchParameters/index.js
@@ -7,9 +7,9 @@ var isEqual = require('lodash/isEqual');
 var isUndefined = require('lodash/isUndefined');
 var isFunction = require('lodash/isFunction');
 
-var defaults = require('lodash/defaults');
 var merge = require('lodash/merge');
 
+var defaultsPure = require('../functions/defaultsPure');
 var find = require('../functions/find');
 var valToNumber = require('../functions/valToNumber');
 var omit = require('../functions/omit');
@@ -1020,7 +1020,7 @@ SearchParameters.prototype = {
     }
 
     return this.setQueryParameters({
-      hierarchicalFacetsRefinements: defaults({}, mod, this.hierarchicalFacetsRefinements)
+      hierarchicalFacetsRefinements: defaultsPure({}, mod, this.hierarchicalFacetsRefinements)
     });
   },
 
@@ -1038,7 +1038,7 @@ SearchParameters.prototype = {
     var mod = {};
     mod[facet] = [path];
     return this.setQueryParameters({
-      hierarchicalFacetsRefinements: defaults({}, mod, this.hierarchicalFacetsRefinements)
+      hierarchicalFacetsRefinements: defaultsPure({}, mod, this.hierarchicalFacetsRefinements)
     });
   },
 
@@ -1055,7 +1055,7 @@ SearchParameters.prototype = {
     var mod = {};
     mod[facet] = [];
     return this.setQueryParameters({
-      hierarchicalFacetsRefinements: defaults({}, mod, this.hierarchicalFacetsRefinements)
+      hierarchicalFacetsRefinements: defaultsPure({}, mod, this.hierarchicalFacetsRefinements)
     });
   },
   /**
diff --git a/src/SearchResults/index.js b/src/SearchResults/index.js
index 45fd059e6..ded126d8c 100644
--- a/src/SearchResults/index.js
+++ b/src/SearchResults/index.js
@@ -2,7 +2,6 @@
 
 var orderBy = require('lodash/orderBy');
 
-var defaults = require('lodash/defaults');
 var merge = require('lodash/merge');
 
 var isFunction = require('lodash/isFunction');
@@ -10,6 +9,7 @@ var isFunction = require('lodash/isFunction');
 var partial = require('lodash/partial');
 var partialRight = require('lodash/partialRight');
 
+var defaultsPure = require('../functions/defaultsPure');
 var compact = require('../functions/compact');
 var find = require('../functions/find');
 var findIndex = require('../functions/findIndex');
@@ -462,7 +462,7 @@ function SearchResults(state, results) {
 
         self.disjunctiveFacets[position] = {
           name: dfacet,
-          data: defaults({}, facetResults, dataFromMainRequest),
+          data: defaultsPure({}, facetResults, dataFromMainRequest),
           exhaustive: result.exhaustiveFacetsCount
         };
         assignFacetStats(self.disjunctiveFacets[position], result.facets_stats, dfacet);
@@ -526,7 +526,7 @@ function SearchResults(state, results) {
         defaultData[root] = self.hierarchicalFacets[position][attributeIndex].data[root];
       }
 
-      self.hierarchicalFacets[position][attributeIndex].data = defaults(
+      self.hierarchicalFacets[position][attributeIndex].data = defaultsPure(
         defaultData,
         facetResults,
         self.hierarchicalFacets[position][attributeIndex].data
@@ -697,7 +697,7 @@ SearchResults.prototype.getFacetValues = function(attribute, opts) {
   var facetValues = extractNormalizedFacetValues(this, attribute);
   if (!facetValues) throw new Error(attribute + ' is not a retrieved facet.');
 
-  var options = defaults({}, opts, {sortBy: SearchResults.DEFAULT_SORT});
+  var options = defaultsPure({}, opts, {sortBy: SearchResults.DEFAULT_SORT});
 
   if (Array.isArray(options.sortBy)) {
     var order = formatSort(options.sortBy, SearchResults.DEFAULT_SORT);
diff --git a/src/functions/defaultsPure.js b/src/functions/defaultsPure.js
new file mode 100644
index 000000000..cb93246dd
--- /dev/null
+++ b/src/functions/defaultsPure.js
@@ -0,0 +1,14 @@
+'use strict';
+
+// NOTE: this behaves like lodash/defaults, but doesn't mutate the target
+module.exports = function defaultsPure() {
+  const sources = Array.prototype.slice.call(arguments);
+  return sources.reduceRight(function(acc, source) {
+    Object.keys(Object(source)).forEach(function(key) {
+      if (source[key] !== undefined) {
+        acc[key] = source[key];
+      }
+    });
+    return acc;
+  }, {});
+};
diff --git a/test/spec/functions/defaultsPure.js b/test/spec/functions/defaultsPure.js
new file mode 100644
index 000000000..ca13ece14
--- /dev/null
+++ b/test/spec/functions/defaultsPure.js
@@ -0,0 +1,66 @@
+'use strict';
+
+var clone = require('lodash/clone');
+var defaults = require('../../../src/functions/defaultsPure');
+
+// tests modified from lodash source
+
+it('should assign source properties if missing on `object`', function() {
+  var actual = defaults({'a': 1}, {'a': 2, 'b': 2});
+  expect(actual).toEqual({'a': 1, 'b': 2});
+});
+
+it('should accept multiple sources', function() {
+  var expected = {'a': 1, 'b': 2, 'c': 3};
+  var actual = defaults({'a': 1, 'b': 2}, {'b': 3}, {'c': 3});
+
+  expect(actual).toEqual(expected);
+
+  actual = defaults({'a': 1, 'b': 2}, {'b': 3, 'c': 3}, {'c': 2});
+  expect(actual).toEqual(expected);
+});
+
+it('should not overwrite `null` values', function() {
+  var actual = defaults({'a': null}, {'a': 1});
+  expect(actual.a).toBe(null);
+});
+
+it('should overwrite `undefined` values', function() {
+  var actual = defaults({'a': undefined}, {'a': 1});
+  expect(actual.a).toBe(1);
+});
+
+it('should assign `undefined` values', function() {
+  var source = {'a': undefined, 'b': 1};
+  var actual = defaults({}, source);
+
+  expect(actual).toEqual({'a': undefined, 'b': 1});
+});
+
+it('should assign properties that shadow those on `Object.prototype`', function() {
+  var object = {
+    'constructor': Object.prototype.constructor,
+    'hasOwnProperty': Object.prototype.hasOwnProperty,
+    'isPrototypeOf': Object.prototype.isPrototypeOf,
+    'propertyIsEnumerable': Object.prototype.propertyIsEnumerable,
+    'toLocaleString': Object.prototype.toLocaleString,
+    'toString': Object.prototype.toString,
+    'valueOf': Object.prototype.valueOf
+  };
+
+  var source = {
+    'constructor': 1,
+    'hasOwnProperty': 2,
+    'isPrototypeOf': 3,
+    'propertyIsEnumerable': 4,
+    'toLocaleString': 5,
+    'toString': 6,
+    'valueOf': 7
+  };
+
+  var expected = clone(source);
+  expect(defaults({}, source)).toEqual(expected);
+
+  expected = clone(object);
+  expect(defaults({}, object, source)).toEqual(expected);
+});