diff --git a/types/mongoose/index.d.ts b/types/mongoose/index.d.ts
index fbdad58c4b..5eea1625b5 100644
--- a/types/mongoose/index.d.ts
+++ b/types/mongoose/index.d.ts
@@ -151,7 +151,8 @@ declare module "mongoose" {
    * @param fn plugin callback
    * @param opts optional options
    */
-  export function plugin<T>(fn: Function, opts?: T): typeof mongoose;
+  export function plugin(fn: Function): typeof mongoose;
+  export function plugin<T>(fn: Function, opts: T): typeof mongoose;
 
   /** Sets mongoose options */
   export function set(key: string, value: any): void;
@@ -655,7 +656,8 @@ declare module "mongoose" {
      * Registers a plugin for this schema.
      * @param plugin callback
      */
-    plugin<T>(plugin: (schema: Schema, options?: T) => void, opts?: T): this;
+    plugin(plugin: (schema: Schema) => void): this;
+    plugin<T>(plugin: (schema: Schema, options: T) => void, opts: T): this;
 
     /**
      * Defines a post hook for the document
diff --git a/types/mongoose/mongoose-tests.ts b/types/mongoose/mongoose-tests.ts
index cadc7d9a83..2fe1e1b12e 100644
--- a/types/mongoose/mongoose-tests.ts
+++ b/types/mongoose/mongoose-tests.ts
@@ -293,7 +293,7 @@ schema.method('name', cb).method({
 });
 schema.path('a', mongoose.Schema.Types.Buffer).path('a');
 schema.pathType('m1').toLowerCase();
-schema.plugin(function (schema, opts) {
+schema.plugin(function (schema: mongoose.Schema, opts?: any) {
   schema.get('path');
   if (opts) {
     opts.hasOwnProperty('');
@@ -564,25 +564,25 @@ new mongoose.Schema({
   }
 });
 
-(new mongoose.Schema({})).plugin(function (schema: any, options: any) {
+(new mongoose.Schema({})).plugin<any>(function (schema: mongoose.Schema, options: any) {
   schema.add({ lastMod: Date })
   schema.pre('save', function (next: Function) {
-    this.lastMod = new Date
+    (this as any).lastMod = new Date
     next()
   })
   if (options && options['index']) {
     schema.path('lastMod').index(options['index'])
   }
-}, { index: true }).plugin(function (schema: any, options: any) {
+}, { index: true }).plugin<any>(function (schema: mongoose.Schema, options: any) {
   schema.add({ lastMod: Date })
   schema.pre('save', function (next: Function) {
-    this.lastMod = new Date
+    (this as any).lastMod = new Date
     next()
   })
   if (options && options['index']) {
     schema.path('lastMod').index(options['index'])
   }
-});
+}, {index: true});
 
 new mongoose.Schema({foo: String}, {strict: 'throw'});
 
@@ -593,6 +593,11 @@ export default function(schema: mongoose.Schema) {
 }
 
 // plugins
+function MyPlugin(schema: mongoose.Schema, opts?: string) {
+}
+new mongoose.Schema({})
+    .plugin(MyPlugin)
+
 interface PluginOption {
     modelName: string;
     timestamp: string;
@@ -602,7 +607,7 @@ function logger(modelName: string, timestamp: string) {
     // call special logger with options
 }
 
-function AwesomeLoggerPlugin(schema: mongoose.Schema, options?: PluginOption) {
+function AwesomeLoggerPlugin(schema: mongoose.Schema, options: PluginOption) {
     if (options) {
         schema.pre('save', function (next: Function) {
             logger(options.modelName, options.timestamp)
diff --git a/types/mongoose/v3/index.d.ts b/types/mongoose/v3/index.d.ts
index b38a20179c..40e254deda 100644
--- a/types/mongoose/v3/index.d.ts
+++ b/types/mongoose/v3/index.d.ts
@@ -14,7 +14,8 @@ declare module "mongoose" {
 
   function model<T extends Document>(name: string, schema?: Schema, collection?: string, skipInit?: boolean): Model<T>;
   function modelNames(): string[];
-  function plugin<T>(plugin: (schema: Schema, options?: T) => void, options?: T): Mongoose;
+  function plugin(plugin: (schema: Schema) => void): Mongoose;
+  function plugin<T>(plugin: (schema: Schema, options: T) => void, options: T): Mongoose;
 
   function get(key: string): any;
   function set(key: string, value: any): void;
@@ -33,7 +34,8 @@ declare module "mongoose" {
     get(key: string): any;
     model<T extends Document>(name: string, schema?: Schema, collection?: string, skipInit?: boolean): Model<T>;
     modelNames(): string[];
-    plugin<T>(plugin: (schema: Schema, options?: T) => void, options?: T): Mongoose;
+    plugin(plugin: (schema: Schema) => void): Mongoose;
+    plugin<T>(plugin: (schema: Schema, options: T) => void, options: T): Mongoose;
     set(key: string, value: any): void;
 
     mongo: any;
@@ -273,7 +275,8 @@ declare module "mongoose" {
     path(path: string): any;
     path(path: string, constructor: any): Schema;
     pathType(path: string): string;
-    plugin<T>(plugin: (schema: Schema, options?: T) => void, options?: T): Schema;
+    plugin(plugin: (schema: Schema) => void): Schema;
+    plugin<T>(plugin: (schema: Schema, options: T) => void, options: T): Schema;
 
     pre(method: string, fn: HookSyncCallback, errorCb?: HookErrorCallback): Schema;
     pre(method: string, isAsync: boolean, fn: HookAsyncCallback, errorCb?: HookErrorCallback): Schema;
diff --git a/types/mongoose/v4/index.d.ts b/types/mongoose/v4/index.d.ts
index 6dfd75308a..ee3cd4c045 100644
--- a/types/mongoose/v4/index.d.ts
+++ b/types/mongoose/v4/index.d.ts
@@ -173,7 +173,8 @@ declare module "mongoose" {
    * @param fn plugin callback
    * @param opts optional options
    */
-  export function plugin<T>(fn: Function, opts?: T): typeof mongoose;
+  export function plugin(fn: Function): typeof mongoose;
+  export function plugin<T>(fn: Function, opts: T): typeof mongoose;
 
   /** Sets mongoose options */
   export function set(key: string, value: any): void;
@@ -678,7 +679,8 @@ declare module "mongoose" {
      * Registers a plugin for this schema.
      * @param plugin callback
      */
-    plugin<T>(plugin: (schema: Schema, options?: T) => void, opts?: T): this;
+    plugin(plugin: (schema: Schema) => void): this;
+    plugin<T>(plugin: (schema: Schema, options: T) => void, opts: T): this;
 
     /**
      * Defines a post hook for the document
diff --git a/types/mongoose/v4/mongoose-tests.ts b/types/mongoose/v4/mongoose-tests.ts
index ddf96848b9..b2d2a834fd 100644
--- a/types/mongoose/v4/mongoose-tests.ts
+++ b/types/mongoose/v4/mongoose-tests.ts
@@ -262,7 +262,7 @@ schema.method('name', cb).method({
 });
 schema.path('a', mongoose.Schema.Types.Buffer).path('a');
 schema.pathType('m1').toLowerCase();
-schema.plugin(function (schema, opts) {
+schema.plugin(function (schema: mongoose.Schema, opts?: any) {
   schema.get('path');
   if (opts) {
     opts.hasOwnProperty('');
@@ -424,7 +424,7 @@ new mongoose.Schema({
   if (options && options['index']) {
     schema.path('lastMod').index(options['index'])
   }
-});
+}, {index: true});
 
 // plugins
 interface PluginOption {