diff --git a/js/src/jsarray.cpp b/js/src/jsarray.cpp
index 3917be60f26..5201ebb3b05 100644
--- a/js/src/jsarray.cpp
+++ b/js/src/jsarray.cpp
@@ -3229,7 +3229,9 @@ static const JSFunctionSpec array_methods[] = {
     JS_SELF_HOSTED_FN("keys",        "ArrayKeys",        0,0),
 
     /* ES7 additions */
+#ifdef NIGHTLY_BUILD
     JS_SELF_HOSTED_FN("includes",    "ArrayIncludes",    2,0),
+#endif
 
     JS_FS_END
 };
diff --git a/js/src/tests/ecma_7/Array/includes.js b/js/src/tests/ecma_7/Array/includes.js
index aa439571ce3..f7daebf05d6 100644
--- a/js/src/tests/ecma_7/Array/includes.js
+++ b/js/src/tests/ecma_7/Array/includes.js
@@ -8,40 +8,42 @@ var summary = "Implement Array.prototype.includes";
 
 print(BUGNUMBER + ": " + summary);
 
-assertEq(typeof [].includes, "function");
-assertEq([].includes.length, 1);
+if ('includes' in []) {
+    assertEq(typeof [].includes, "function");
+    assertEq([].includes.length, 1);
 
-assertTrue([1, 2, 3].includes(2));
-assertTrue([1,,2].includes(2));
-assertTrue([1, 2, 3].includes(2, 1));
-assertTrue([1, 2, 3].includes(2, -2));
-assertTrue([1, 2, 3].includes(2, -100));
-assertTrue([Object, Function, Array].includes(Function));
-assertTrue([-0].includes(0));
-assertTrue([NaN].includes(NaN));
-assertTrue([,].includes());
-assertTrue(staticIncludes("123", "2"));
-assertTrue(staticIncludes({length: 3, 1: 2}, 2));
-assertTrue(staticIncludes({length: 3, 1: 2, get 3(){throw ""}}, 2));
-assertTrue(staticIncludes({length: 3, get 1() {return 2}}, 2));
-assertTrue(staticIncludes({__proto__: {1: 2}, length: 3}, 2));
-assertTrue(staticIncludes(new Proxy([1], {get(){return 2}}), 2));
+    assertTrue([1, 2, 3].includes(2));
+    assertTrue([1,,2].includes(2));
+    assertTrue([1, 2, 3].includes(2, 1));
+    assertTrue([1, 2, 3].includes(2, -2));
+    assertTrue([1, 2, 3].includes(2, -100));
+    assertTrue([Object, Function, Array].includes(Function));
+    assertTrue([-0].includes(0));
+    assertTrue([NaN].includes(NaN));
+    assertTrue([,].includes());
+    assertTrue(staticIncludes("123", "2"));
+    assertTrue(staticIncludes({length: 3, 1: 2}, 2));
+    assertTrue(staticIncludes({length: 3, 1: 2, get 3(){throw ""}}, 2));
+    assertTrue(staticIncludes({length: 3, get 1() {return 2}}, 2));
+    assertTrue(staticIncludes({__proto__: {1: 2}, length: 3}, 2));
+    assertTrue(staticIncludes(new Proxy([1], {get(){return 2}}), 2));
 
-assertFalse([1, 2, 3].includes("2"));
-assertFalse([1, 2, 3].includes(2, 2));
-assertFalse([1, 2, 3].includes(2, -1));
-assertFalse([undefined].includes(NaN));
-assertFalse([{}].includes({}));
-assertFalse(staticIncludes({length: 3, 1: 2}, 2, 2));
-assertFalse(staticIncludes({length: 3, get 0(){delete this[1]}, 1: 2}, 2));
-assertFalse(staticIncludes({length: -100, 0: 1}, 1));
+    assertFalse([1, 2, 3].includes("2"));
+    assertFalse([1, 2, 3].includes(2, 2));
+    assertFalse([1, 2, 3].includes(2, -1));
+    assertFalse([undefined].includes(NaN));
+    assertFalse([{}].includes({}));
+    assertFalse(staticIncludes({length: 3, 1: 2}, 2, 2));
+    assertFalse(staticIncludes({length: 3, get 0(){delete this[1]}, 1: 2}, 2));
+    assertFalse(staticIncludes({length: -100, 0: 1}, 1));
 
-assertThrowsInstanceOf(() => staticIncludes(), TypeError);
-assertThrowsInstanceOf(() => staticIncludes(null), TypeError);
-assertThrowsInstanceOf(() => staticIncludes({get length(){throw TypeError()}}), TypeError);
-assertThrowsInstanceOf(() => staticIncludes({length: 3, get 1() {throw TypeError()}}, 2), TypeError);
-assertThrowsInstanceOf(() => staticIncludes({__proto__: {get 1() {throw TypeError()}}, length: 3}, 2), TypeError);
-assertThrowsInstanceOf(() => staticIncludes(new Proxy([1], {get(){throw TypeError()}})), TypeError);
+    assertThrowsInstanceOf(() => staticIncludes(), TypeError);
+    assertThrowsInstanceOf(() => staticIncludes(null), TypeError);
+    assertThrowsInstanceOf(() => staticIncludes({get length(){throw TypeError()}}), TypeError);
+    assertThrowsInstanceOf(() => staticIncludes({length: 3, get 1() {throw TypeError()}}, 2), TypeError);
+    assertThrowsInstanceOf(() => staticIncludes({__proto__: {get 1() {throw TypeError()}}, length: 3}, 2), TypeError);
+    assertThrowsInstanceOf(() => staticIncludes(new Proxy([1], {get(){throw TypeError()}})), TypeError);
+}
 
 function assertTrue(v) {
     assertEq(v, true);
diff --git a/js/xpconnect/tests/chrome/test_xrayToJS.xul b/js/xpconnect/tests/chrome/test_xrayToJS.xul
index f933fb8d09c..be176687759 100644
--- a/js/xpconnect/tests/chrome/test_xrayToJS.xul
+++ b/js/xpconnect/tests/chrome/test_xrayToJS.xul
@@ -169,8 +169,9 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=933681
     ["length", "toSource", "toString", "toLocaleString", "join", "reverse", "sort", "push",
       "pop", "shift", "unshift", "splice", "concat", "slice", "lastIndexOf", "indexOf",
       "forEach", "map", "reduce", "reduceRight", "filter", "some", "every", "find",
-      "findIndex", "copyWithin", "fill", "includes", kIteratorSymbol, "entries", "keys", "constructor"];
+      "findIndex", "copyWithin", "fill", kIteratorSymbol, "entries", "keys", "constructor"];
   if (isNightlyBuild) {
+    gPrototypeProperties['Array'].push('includes');
     let pjsMethods = ['mapPar', 'reducePar', 'scanPar', 'scatterPar', 'filterPar'];
     gPrototypeProperties['Array'] = gPrototypeProperties['Array'].concat(pjsMethods);
   }