diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 44cb0ea3ccfe1..8fed6ee42f9e9 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -6100,6 +6100,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
                 if (contains(externalImports, node)) {
                     const isExportedImport = node.kind === SyntaxKind.ImportEqualsDeclaration && (node.flags & NodeFlags.Export) !== 0;
                     const namespaceDeclaration = getNamespaceDeclarationNode(node);
+                    const varOrConst = (languageVersion <= ScriptTarget.ES5) ? "var " : "const ";
 
                     if (modulekind !== ModuleKind.AMD) {
                         emitLeadingComments(node);
@@ -6107,7 +6108,9 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
                         if (namespaceDeclaration && !isDefaultImport(node)) {
                             // import x = require("foo")
                             // import * as x from "foo"
-                            if (!isExportedImport) write("var ");
+                            if (!isExportedImport) {
+                                write(varOrConst);
+                            };
                             emitModuleMemberName(namespaceDeclaration);
                             write(" = ");
                         }
@@ -6119,7 +6122,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
                             // import d, { x, y } from "foo"
                             const isNakedImport = SyntaxKind.ImportDeclaration && !(<ImportDeclaration>node).importClause;
                             if (!isNakedImport) {
-                                write("var ");
+                                write(varOrConst);
                                 write(getGeneratedNameForNode(<ImportDeclaration>node));
                                 write(" = ");
                             }
@@ -6146,7 +6149,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
                         }
                         else if (namespaceDeclaration && isDefaultImport(node)) {
                             // import d, * as x from "foo"
-                            write("var ");
+                            write(varOrConst);
                             emitModuleMemberName(namespaceDeclaration);
                             write(" = ");
                             write(getGeneratedNameForNode(<ImportDeclaration>node));
diff --git a/tests/baselines/reference/asyncImportedPromise_es6.js b/tests/baselines/reference/asyncImportedPromise_es6.js
index d861012488cff..a63d7844f4cd5 100644
--- a/tests/baselines/reference/asyncImportedPromise_es6.js
+++ b/tests/baselines/reference/asyncImportedPromise_es6.js
@@ -24,7 +24,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
         step((generator = generator.call(thisArg, _arguments)).next());
     });
 };
-var task_1 = require("./task");
+const task_1 = require("./task");
 class Test {
     example() {
         return __awaiter(this, void 0, task_1.Task, function* () { return; });
diff --git a/tests/baselines/reference/es6ImportDefaultBindingFollowedWithNamedImport.js b/tests/baselines/reference/es6ImportDefaultBindingFollowedWithNamedImport.js
index d7dfe29208d0d..4bff2abf82d56 100644
--- a/tests/baselines/reference/es6ImportDefaultBindingFollowedWithNamedImport.js
+++ b/tests/baselines/reference/es6ImportDefaultBindingFollowedWithNamedImport.js
@@ -31,16 +31,16 @@ Object.defineProperty(exports, "__esModule", { value: true });
 exports.default = {};
 //// [es6ImportDefaultBindingFollowedWithNamedImport_1.js]
 "use strict";
-var es6ImportDefaultBindingFollowedWithNamedImport_0_1 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
+const es6ImportDefaultBindingFollowedWithNamedImport_0_1 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
 var x1 = es6ImportDefaultBindingFollowedWithNamedImport_0_1.a;
-var es6ImportDefaultBindingFollowedWithNamedImport_0_2 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
+const es6ImportDefaultBindingFollowedWithNamedImport_0_2 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
 var x1 = es6ImportDefaultBindingFollowedWithNamedImport_0_2.a;
-var es6ImportDefaultBindingFollowedWithNamedImport_0_3 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
+const es6ImportDefaultBindingFollowedWithNamedImport_0_3 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
 var x1 = es6ImportDefaultBindingFollowedWithNamedImport_0_3.x;
 var x1 = es6ImportDefaultBindingFollowedWithNamedImport_0_3.a;
-var es6ImportDefaultBindingFollowedWithNamedImport_0_4 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
+const es6ImportDefaultBindingFollowedWithNamedImport_0_4 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
 var x1 = es6ImportDefaultBindingFollowedWithNamedImport_0_4.x;
-var es6ImportDefaultBindingFollowedWithNamedImport_0_5 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
+const es6ImportDefaultBindingFollowedWithNamedImport_0_5 = require("./es6ImportDefaultBindingFollowedWithNamedImport_0");
 var x1 = es6ImportDefaultBindingFollowedWithNamedImport_0_5.m;
 
 
diff --git a/tests/baselines/reference/es6ImportNameSpaceImport.js b/tests/baselines/reference/es6ImportNameSpaceImport.js
index 685e1cf643c24..8e109779f45fb 100644
--- a/tests/baselines/reference/es6ImportNameSpaceImport.js
+++ b/tests/baselines/reference/es6ImportNameSpaceImport.js
@@ -15,7 +15,7 @@ import * as nameSpaceBinding2 from "./es6ImportNameSpaceImport_0"; // elide this
 exports.a = 10;
 //// [es6ImportNameSpaceImport_1.js]
 "use strict";
-var nameSpaceBinding = require("./es6ImportNameSpaceImport_0");
+const nameSpaceBinding = require("./es6ImportNameSpaceImport_0");
 var x = nameSpaceBinding.a;
 
 
diff --git a/tests/baselines/reference/es6ImportNamedImport.js b/tests/baselines/reference/es6ImportNamedImport.js
index 73fe8f4ec1b4f..8dbdf7ce6f195 100644
--- a/tests/baselines/reference/es6ImportNamedImport.js
+++ b/tests/baselines/reference/es6ImportNamedImport.js
@@ -53,26 +53,26 @@ exports.z2 = 10;
 exports.aaaa = 10;
 //// [es6ImportNamedImport_1.js]
 "use strict";
-var es6ImportNamedImport_0_1 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_1 = require("./es6ImportNamedImport_0");
 var xxxx = es6ImportNamedImport_0_1.a;
-var es6ImportNamedImport_0_2 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_2 = require("./es6ImportNamedImport_0");
 var xxxx = es6ImportNamedImport_0_2.a;
-var es6ImportNamedImport_0_3 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_3 = require("./es6ImportNamedImport_0");
 var xxxx = es6ImportNamedImport_0_3.x;
 var xxxx = es6ImportNamedImport_0_3.a;
-var es6ImportNamedImport_0_4 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_4 = require("./es6ImportNamedImport_0");
 var xxxx = es6ImportNamedImport_0_4.x;
-var es6ImportNamedImport_0_5 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_5 = require("./es6ImportNamedImport_0");
 var xxxx = es6ImportNamedImport_0_5.m;
-var es6ImportNamedImport_0_6 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_6 = require("./es6ImportNamedImport_0");
 var xxxx = es6ImportNamedImport_0_6.a1;
 var xxxx = es6ImportNamedImport_0_6.x1;
-var es6ImportNamedImport_0_7 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_7 = require("./es6ImportNamedImport_0");
 var xxxx = es6ImportNamedImport_0_7.a1;
 var xxxx = es6ImportNamedImport_0_7.x1;
-var es6ImportNamedImport_0_8 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_8 = require("./es6ImportNamedImport_0");
 var z111 = es6ImportNamedImport_0_8.z1;
-var es6ImportNamedImport_0_9 = require("./es6ImportNamedImport_0");
+const es6ImportNamedImport_0_9 = require("./es6ImportNamedImport_0");
 var z2 = es6ImportNamedImport_0_9.z2; // z2 shouldn't give redeclare error
 
 
diff --git a/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js b/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js
index b67f61e88aece..38766d32cd900 100644
--- a/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js
+++ b/tests/baselines/reference/es6ImportNamedImportInExportAssignment.js
@@ -13,7 +13,7 @@ export = a;
 exports.a = 10;
 //// [es6ImportNamedImportInExportAssignment_1.js]
 "use strict";
-var es6ImportNamedImportInExportAssignment_0_1 = require("./es6ImportNamedImportInExportAssignment_0");
+const es6ImportNamedImportInExportAssignment_0_1 = require("./es6ImportNamedImportInExportAssignment_0");
 module.exports = es6ImportNamedImportInExportAssignment_0_1.a;
 
 
diff --git a/tests/baselines/reference/exportsAndImports1-es6.js b/tests/baselines/reference/exportsAndImports1-es6.js
index ece98a80318c8..3ac5aeb0dc5e9 100644
--- a/tests/baselines/reference/exportsAndImports1-es6.js
+++ b/tests/baselines/reference/exportsAndImports1-es6.js
@@ -67,7 +67,7 @@ exports.M = t1_1.M;
 exports.a = t1_1.a;
 //// [t3.js]
 "use strict";
-var t1_1 = require("./t1");
+const t1_1 = require("./t1");
 exports.v = t1_1.v;
 exports.f = t1_1.f;
 exports.C = t1_1.C;
diff --git a/tests/baselines/reference/exportsAndImports2-es6.js b/tests/baselines/reference/exportsAndImports2-es6.js
index 865534b285137..56639bdbecf2e 100644
--- a/tests/baselines/reference/exportsAndImports2-es6.js
+++ b/tests/baselines/reference/exportsAndImports2-es6.js
@@ -24,6 +24,6 @@ exports.y = t1_1.x;
 exports.x = t1_1.y;
 //// [t3.js]
 "use strict";
-var t1_1 = require("./t1");
+const t1_1 = require("./t1");
 exports.y = t1_1.x;
 exports.x = t1_1.y;
diff --git a/tests/baselines/reference/exportsAndImports3-es6.js b/tests/baselines/reference/exportsAndImports3-es6.js
index ed509d31437b6..ea16836b1f202 100644
--- a/tests/baselines/reference/exportsAndImports3-es6.js
+++ b/tests/baselines/reference/exportsAndImports3-es6.js
@@ -69,7 +69,7 @@ exports.M = t1_1.M1;
 exports.a = t1_1.a1;
 //// [t3.js]
 "use strict";
-var t1_1 = require("./t1");
+const t1_1 = require("./t1");
 exports.v = t1_1.v1;
 exports.f = t1_1.f1;
 exports.C = t1_1.C1;
diff --git a/tests/baselines/reference/exportsAndImports4-es6.js b/tests/baselines/reference/exportsAndImports4-es6.js
index 39c6583e9359f..8a8d4f812254e 100644
--- a/tests/baselines/reference/exportsAndImports4-es6.js
+++ b/tests/baselines/reference/exportsAndImports4-es6.js
@@ -45,24 +45,24 @@ Object.defineProperty(exports, "__esModule", { value: true });
 exports.default = "hello";
 //// [t3.js]
 "use strict";
-var a = require("./t1");
+const a = require("./t1");
 exports.a = a;
 a.default;
-var t1_1 = require("./t1");
+const t1_1 = require("./t1");
 exports.b = t1_1.default;
 t1_1.default;
-var c = require("./t1");
+const c = require("./t1");
 exports.c = c;
 c.default;
-var t1_2 = require("./t1");
+const t1_2 = require("./t1");
 exports.d = t1_2.default;
 t1_2.default;
-var t1_3 = require("./t1"), e2 = t1_3;
+const t1_3 = require("./t1"), e2 = t1_3;
 exports.e1 = t1_3.default;
 exports.e2 = e2;
 t1_3.default;
 e2.default;
-var t1_4 = require("./t1");
+const t1_4 = require("./t1");
 exports.f1 = t1_4.default;
 exports.f2 = t1_4.default;
 t1_4.default;
diff --git a/tests/baselines/reference/shorthandPropertyAssignmentInES6Module.js b/tests/baselines/reference/shorthandPropertyAssignmentInES6Module.js
index cab16b96bc305..d52622dffc7d8 100644
--- a/tests/baselines/reference/shorthandPropertyAssignmentInES6Module.js
+++ b/tests/baselines/reference/shorthandPropertyAssignmentInES6Module.js
@@ -20,8 +20,8 @@ use(foo);
 exports.x = 1;
 //// [test.js]
 "use strict";
-var existingModule_1 = require('./existingModule');
-var missingModule_1 = require('./missingModule');
+const existingModule_1 = require('./existingModule');
+const missingModule_1 = require('./missingModule');
 const test = { x: existingModule_1.x, foo: missingModule_1.foo };
 use(existingModule_1.x);
 use(missingModule_1.foo);