diff --git a/tests/baselines/reference/commonSourceDirectory.js b/tests/baselines/reference/commonSourceDirectory.js
index 3babba98337..5299095ae74 100644
--- a/tests/baselines/reference/commonSourceDirectory.js
+++ b/tests/baselines/reference/commonSourceDirectory.js
@@ -5,12 +5,21 @@
 
 export const x = 0;
 
+//// [bar.d.ts]
+declare module "bar" {
+    export const y = 0;
+}
+
 //// [index.ts]
+/// <reference path="../types/bar.d.ts"/>
 import { x } from "foo";
-x + 1;
+import { y } from "bar";
+x + y;
 
 
 //// [/app/bin/index.js]
 "use strict";
+/// <reference path="../types/bar.d.ts"/>
 var foo_1 = require("foo");
-foo_1.x + 1;
+var bar_1 = require("bar");
+foo_1.x + bar_1.y;
diff --git a/tests/baselines/reference/commonSourceDirectory.symbols b/tests/baselines/reference/commonSourceDirectory.symbols
index 88ded4c8c87..5409286ede5 100644
--- a/tests/baselines/reference/commonSourceDirectory.symbols
+++ b/tests/baselines/reference/commonSourceDirectory.symbols
@@ -1,9 +1,14 @@
 === /app/index.ts ===
+/// <reference path="../types/bar.d.ts"/>
 import { x } from "foo";
->x : Symbol(x, Decl(index.ts, 0, 8))
+>x : Symbol(x, Decl(index.ts, 1, 8))
 
-x + 1;
->x : Symbol(x, Decl(index.ts, 0, 8))
+import { y } from "bar";
+>y : Symbol(y, Decl(index.ts, 2, 8))
+
+x + y;
+>x : Symbol(x, Decl(index.ts, 1, 8))
+>y : Symbol(y, Decl(index.ts, 2, 8))
 
 === /node_modules/foo/index.ts ===
 // Test that importing a file from `node_modules` does not affect calculation of the common source directory.
@@ -11,3 +16,9 @@ x + 1;
 export const x = 0;
 >x : Symbol(x, Decl(index.ts, 2, 12))
 
+=== /types/bar.d.ts ===
+declare module "bar" {
+    export const y = 0;
+>y : Symbol(y, Decl(bar.d.ts, 1, 16))
+}
+
diff --git a/tests/baselines/reference/commonSourceDirectory.types b/tests/baselines/reference/commonSourceDirectory.types
index a0c66b86ae0..ce0169582d7 100644
--- a/tests/baselines/reference/commonSourceDirectory.types
+++ b/tests/baselines/reference/commonSourceDirectory.types
@@ -1,11 +1,15 @@
 === /app/index.ts ===
+/// <reference path="../types/bar.d.ts"/>
 import { x } from "foo";
 >x : 0
 
-x + 1;
->x + 1 : number
+import { y } from "bar";
+>y : 0
+
+x + y;
+>x + y : number
 >x : 0
->1 : 1
+>y : 0
 
 === /node_modules/foo/index.ts ===
 // Test that importing a file from `node_modules` does not affect calculation of the common source directory.
@@ -14,3 +18,10 @@ export const x = 0;
 >x : 0
 >0 : 0
 
+=== /types/bar.d.ts ===
+declare module "bar" {
+    export const y = 0;
+>y : 0
+>0 : 0
+}
+
diff --git a/tests/cases/compiler/commonSourceDirectory.ts b/tests/cases/compiler/commonSourceDirectory.ts
index 6583da67c6a..930f922e10d 100644
--- a/tests/cases/compiler/commonSourceDirectory.ts
+++ b/tests/cases/compiler/commonSourceDirectory.ts
@@ -6,13 +6,21 @@
 // @filename: /node_modules/foo/index.ts
 export const x = 0;
 
+// @filename: /types/bar.d.ts
+declare module "bar" {
+    export const y = 0;
+}
+
 // @filename: /app/index.ts
+/// <reference path="../types/bar.d.ts"/>
 import { x } from "foo";
-x + 1;
+import { y } from "bar";
+x + y;
 
 // @filename: /app/tsconfig.json
 {
     "compilerOptions": {
-        "outDir": "bin"
+        "outDir": "bin",
+        "typeRoots": ["../types"]
     }
 }