diff --git a/atom/browser/api/atom_api_session.cc b/atom/browser/api/atom_api_session.cc
index 0c850888e8e7..83d103a631f7 100644
--- a/atom/browser/api/atom_api_session.cc
+++ b/atom/browser/api/atom_api_session.cc
@@ -233,7 +233,7 @@ class ResolveProxyHelper {
  public:
   ResolveProxyHelper(AtomBrowserContext* browser_context,
                      const GURL& url,
-                     Session::ResolveProxyCallback callback)
+                     const Session::ResolveProxyCallback& callback)
       : callback_(callback),
         original_thread_(base::ThreadTaskRunnerHandle::Get()) {
     scoped_refptr<net::URLRequestContextGetter> context_getter =
diff --git a/atom/browser/api/atom_api_web_contents.cc b/atom/browser/api/atom_api_web_contents.cc
index a0100fd65c6e..9390777f9c58 100644
--- a/atom/browser/api/atom_api_web_contents.cc
+++ b/atom/browser/api/atom_api_web_contents.cc
@@ -240,7 +240,7 @@ content::ServiceWorkerContext* GetServiceWorkerContext(
 }
 
 // Called when CapturePage is done.
-void OnCapturePageDone(base::Callback<void(const gfx::Image&)> callback,
+void OnCapturePageDone(const base::Callback<void(const gfx::Image&)>& callback,
                        const SkBitmap& bitmap,
                        content::ReadbackResponse response) {
   callback.Run(gfx::Image::CreateFrom1xBitmap(bitmap));
diff --git a/atom/browser/browser.h b/atom/browser/browser.h
index 28103a99c704..78cac65f7e40 100644
--- a/atom/browser/browser.h
+++ b/atom/browser/browser.h
@@ -102,7 +102,7 @@ class Browser : public WindowListObserver {
     std::vector<base::string16> args;
   };
   void SetLoginItemSettings(LoginItemSettings settings);
-  LoginItemSettings GetLoginItemSettings(LoginItemSettings options);
+  LoginItemSettings GetLoginItemSettings(const LoginItemSettings& options);
 
 #if defined(OS_MACOSX)
   // Hide the application.
diff --git a/atom/browser/browser_linux.cc b/atom/browser/browser_linux.cc
index 6abfcf5c3481..4dd799dfaf02 100644
--- a/atom/browser/browser_linux.cc
+++ b/atom/browser/browser_linux.cc
@@ -64,7 +64,7 @@ void Browser::SetLoginItemSettings(LoginItemSettings settings) {
 }
 
 Browser::LoginItemSettings Browser::GetLoginItemSettings(
-    LoginItemSettings options) {
+    const LoginItemSettings& options) {
   return LoginItemSettings();
 }
 
diff --git a/atom/browser/browser_mac.mm b/atom/browser/browser_mac.mm
index c318cf850701..bbc848cb6990 100644
--- a/atom/browser/browser_mac.mm
+++ b/atom/browser/browser_mac.mm
@@ -152,7 +152,7 @@ bool Browser::ContinueUserActivity(const std::string& type,
 }
 
 Browser::LoginItemSettings Browser::GetLoginItemSettings(
-    LoginItemSettings options) {
+    const LoginItemSettings& options) {
   LoginItemSettings settings;
   settings.open_at_login = base::mac::CheckLoginItemStatus(
       &settings.open_as_hidden);
diff --git a/atom/browser/browser_win.cc b/atom/browser/browser_win.cc
index 85990bbc67e3..50a9f9da330e 100644
--- a/atom/browser/browser_win.cc
+++ b/atom/browser/browser_win.cc
@@ -287,7 +287,7 @@ void Browser::SetLoginItemSettings(LoginItemSettings settings) {
 }
 
 Browser::LoginItemSettings Browser::GetLoginItemSettings(
-    LoginItemSettings options) {
+    const LoginItemSettings& options) {
   LoginItemSettings settings;
   base::string16 keyPath = L"Software\\Microsoft\\Windows\\CurrentVersion\\Run";
   base::win::RegKey key(HKEY_CURRENT_USER, keyPath.c_str(), KEY_ALL_ACCESS);
diff --git a/atom/renderer/atom_sandboxed_renderer_client.cc b/atom/renderer/atom_sandboxed_renderer_client.cc
index bf9ea6fd9ef8..fe10860621a9 100644
--- a/atom/renderer/atom_sandboxed_renderer_client.cc
+++ b/atom/renderer/atom_sandboxed_renderer_client.cc
@@ -236,7 +236,7 @@ void AtomSandboxedRendererClient::WillReleaseScriptContext(
 
 void AtomSandboxedRendererClient::InvokeIpcCallback(
     v8::Handle<v8::Context> context,
-    std::string callback_name,
+    const std::string& callback_name,
     std::vector<v8::Handle<v8::Value>> args) {
   auto isolate = context->GetIsolate();
   auto binding_key = mate::ConvertToV8(isolate, kIpcKey)->ToString();
diff --git a/atom/renderer/atom_sandboxed_renderer_client.h b/atom/renderer/atom_sandboxed_renderer_client.h
index 0912c6b24bd0..6754e0cb89d4 100644
--- a/atom/renderer/atom_sandboxed_renderer_client.h
+++ b/atom/renderer/atom_sandboxed_renderer_client.h
@@ -22,7 +22,7 @@ class AtomSandboxedRendererClient : public content::ContentRendererClient {
   void WillReleaseScriptContext(
       v8::Handle<v8::Context> context, content::RenderFrame* render_frame);
   void InvokeIpcCallback(v8::Handle<v8::Context> context,
-                         std::string callback_name,
+                         const std::string& callback_name,
                          std::vector<v8::Handle<v8::Value>> args);
   // content::ContentRendererClient:
   void RenderFrameCreated(content::RenderFrame*) override;