diff --git a/src/server/client.ts b/src/server/client.ts
index 2cfd911b7b5..f1c5e424d47 100644
--- a/src/server/client.ts
+++ b/src/server/client.ts
@@ -175,7 +175,7 @@ module ts.server {
         getProjectInfo(fileName: string, needFileNameList: boolean): protocol.ProjectInfo {
             var args: protocol.ProjectInfoRequestArgs = {
                 file: fileName,
-                needFileNameList: !!needFileNameList
+                needFileNameList: needFileNameList
             };
 
             var request = this.processRequest<protocol.ProjectInfoRequest>(CommandNames.ProjectInfo, args);
diff --git a/src/server/protocol.d.ts b/src/server/protocol.d.ts
index 41e25661112..ef9ad7984f6 100644
--- a/src/server/protocol.d.ts
+++ b/src/server/protocol.d.ts
@@ -88,7 +88,7 @@ declare module ts.server.protocol {
     }
 
     /** 
-      * Arguments for ProjectInfoResponse messages.
+      * Arguments for ProjectInfoRequest request.
       */
     export interface ProjectInfoRequestArgs extends FileRequestArgs {
         /**
@@ -97,18 +97,31 @@ declare module ts.server.protocol {
         needFileNameList: boolean;
     }
 
+    /**
+      * A request to get the project information of the current file
+      */
     export interface ProjectInfoRequest extends Request {
         arguments: ProjectInfoRequestArgs
     }
 
     /** 
-      * Response message for "projectInfo" request
+      * Response message body for "projectInfo" request
       */
     export interface ProjectInfo {
+        /**
+          * For configured project, this is the normalized path of the 'tsconfig.json' file
+          * For inferred project, this is undefined
+          */
         configFileName: string;
+        /**
+          * The list of normalized file name in the project, including 'lib.d.ts'
+          */
         fileNameList?: string[];
     }
 
+    /** 
+      * Response message for "projectInfo" request
+      */
     export interface ProjectInfoResponse extends Response {
         body?: ProjectInfo;
     }
diff --git a/tests/cases/fourslash/server/projectInfo.ts b/tests/cases/fourslash/server/projectInfo.ts
index d08c7dd85f1..656647715f0 100644
--- a/tests/cases/fourslash/server/projectInfo.ts
+++ b/tests/cases/fourslash/server/projectInfo.ts
@@ -1,10 +1,24 @@
 /// <reference path="../fourslash.ts"/>
 
 // @Filename: a.ts
-//// import test from "b"
+////export var test = "test String"
 
 // @Filename: b.ts
-//// export var test = "test String"
+////import test from "a"
+
+// @Filename: c.ts
+/////// <reference path="a.ts"/>
+/////// <reference path="b.ts"/>
+
+// @Filename: d.ts
+////console.log("nothing");
 
 goTo.file("a.ts")
-verify.ProjectInfo(["lib.d.ts", "b.ts", "a.ts"])
+verify.ProjectInfo(["lib.d.ts", "a.ts"])
+goTo.file("b.ts")
+verify.ProjectInfo(["lib.d.ts", "a.ts", "b.ts"])
+goTo.file("c.ts")
+verify.ProjectInfo(["lib.d.ts", "a.ts", "b.ts", "c.ts"])
+goTo.file("d.ts")
+verify.ProjectInfo(["lib.d.ts", "d.ts"])
+