diff --git a/src/harness/unittests/extractMethods.ts b/src/harness/unittests/extractMethods.ts
index a7cc73b5b51..43984fc21b8 100644
--- a/src/harness/unittests/extractMethods.ts
+++ b/src/harness/unittests/extractMethods.ts
@@ -574,6 +574,13 @@ namespace A {
         [#|t1.toString();
         t2.toString();|]
     }
+}`);
+        // Confirm that the constraint is preserved.
+        testExtractMethod("extractMethod15",
+            `function F<T>(t1: T) {
+    function F<U extends T[]>(t2: U) {
+        [#|t2.toString();|]
+    }
 }`);
     });
 
@@ -590,7 +597,7 @@ namespace A {
                     path: "/a.ts",
                     content: t.source
                 };
-                const host = projectSystem.createServerHost([f]);
+                const host = projectSystem.createServerHost([f, projectSystem.libFile]);
                 const projectService = projectSystem.createProjectService(host);
                 projectService.openClientFile(f.path);
                 const program = projectService.inferredProjects[0].getLanguageService().getProgram();
diff --git a/tests/baselines/reference/extractMethod/extractMethod15.ts b/tests/baselines/reference/extractMethod/extractMethod15.ts
new file mode 100644
index 00000000000..ba5b9b3ad01
--- /dev/null
+++ b/tests/baselines/reference/extractMethod/extractMethod15.ts
@@ -0,0 +1,35 @@
+// ==ORIGINAL==
+function F<T>(t1: T) {
+    function F<U extends T[]>(t2: U) {
+        t2.toString();
+    }
+}
+// ==SCOPE::function 'F'==
+function F<T>(t1: T) {
+    function F<U extends T[]>(t2: U) {
+        newFunction();
+
+        function newFunction() {
+            t2.toString();
+        }
+    }
+}
+// ==SCOPE::function 'F'==
+function F<T>(t1: T) {
+    function F<U extends T[]>(t2: U) {
+        newFunction<U>(t2);
+    }
+
+    function newFunction<U extends T[]>(t2: U) {
+        t2.toString();
+    }
+}
+// ==SCOPE::global scope==
+function F<T>(t1: T) {
+    function F<U extends T[]>(t2: U) {
+        newFunction<T, U>(t2);
+    }
+}
+function newFunction<T, U extends T[]>(t2: U) {
+    t2.toString();
+}