diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index d132e12e793..bb4d179704c 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -7636,7 +7636,7 @@ const _super = (function (geti, seti) {
             }
 
             function isUseStrictPrologue(node: ExpressionStatement): boolean {
-                return !!(node.expression as StringLiteral).text.match(/use strict/);
+                return (node.expression as StringLiteral).text === "use strict";
             }
 
             function ensureUseStrictPrologue(startWithNewLine: boolean, writeUseStrict: boolean) {
diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index ec5ac638605..9ce03ff77a4 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -1202,7 +1202,7 @@ namespace ts {
     // Utilities
 
     function isUseStrictPrologue(node: ExpressionStatement): boolean {
-        return !!(node.expression as StringLiteral).text.match(/use strict/);
+        return (node.expression as StringLiteral).text === "use strict";
     }
 
     export function addPrologueDirectives(target: Statement[], source: Statement[], ensureUseStrict?: boolean): number {
diff --git a/tests/baselines/reference/useStrictLikePrologueString01.js b/tests/baselines/reference/useStrictLikePrologueString01.js
new file mode 100644
index 00000000000..56df03abfe5
--- /dev/null
+++ b/tests/baselines/reference/useStrictLikePrologueString01.js
@@ -0,0 +1,14 @@
+//// [useStrictLikePrologueString01.ts]
+
+"hey!"
+" use strict "
+export function f() {   
+}
+
+//// [useStrictLikePrologueString01.js]
+"hey!";
+" use strict ";
+"use strict";
+function f() {
+}
+exports.f = f;
diff --git a/tests/baselines/reference/useStrictLikePrologueString01.symbols b/tests/baselines/reference/useStrictLikePrologueString01.symbols
new file mode 100644
index 00000000000..e96d48d9933
--- /dev/null
+++ b/tests/baselines/reference/useStrictLikePrologueString01.symbols
@@ -0,0 +1,7 @@
+=== tests/cases/compiler/useStrictLikePrologueString01.ts ===
+
+"hey!"
+" use strict "
+export function f() {   
+>f : Symbol(f, Decl(useStrictLikePrologueString01.ts, 2, 14))
+}
diff --git a/tests/baselines/reference/useStrictLikePrologueString01.types b/tests/baselines/reference/useStrictLikePrologueString01.types
new file mode 100644
index 00000000000..a12dfe3abd3
--- /dev/null
+++ b/tests/baselines/reference/useStrictLikePrologueString01.types
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/useStrictLikePrologueString01.ts ===
+
+"hey!"
+>"hey!" : string
+
+" use strict "
+>" use strict " : string
+
+export function f() {   
+>f : () => void
+}
diff --git a/tests/cases/compiler/useStrictLikePrologueString01.ts b/tests/cases/compiler/useStrictLikePrologueString01.ts
new file mode 100644
index 00000000000..b76e38ebb06
--- /dev/null
+++ b/tests/cases/compiler/useStrictLikePrologueString01.ts
@@ -0,0 +1,7 @@
+//@target: commonjs
+//@target: es5
+
+"hey!"
+" use strict "
+export function f() {   
+}
\ No newline at end of file