diff --git a/SwiftLintXcode.xcodeproj/project.pbxproj b/SwiftLintXcode.xcodeproj/project.pbxproj
index 6da46d4..21c503f 100644
--- a/SwiftLintXcode.xcodeproj/project.pbxproj
+++ b/SwiftLintXcode.xcodeproj/project.pbxproj
@@ -9,6 +9,7 @@
 /* Begin PBXBuildFile section */
 		0498717F1CB27F8900C5F7B5 /* SwiftLintXcodeTRVSXcode.m in Sources */ = {isa = PBXBuildFile; fileRef = 0498717E1CB27F8900C5F7B5 /* SwiftLintXcodeTRVSXcode.m */; };
 		049871811CB28EBF00C5F7B5 /* Formatter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 049871801CB28EBF00C5F7B5 /* Formatter.swift */; };
+		04DFAD491CB50BC8007998DF /* errorHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04DFAD481CB50BC8007998DF /* errorHelper.swift */; };
 		04E4BF341CB25D3200BC7305 /* SwiftLintXcode.xcscheme in Resources */ = {isa = PBXBuildFile; fileRef = 04E4BF331CB25D3200BC7305 /* SwiftLintXcode.xcscheme */; };
 		04E4BF361CB25D3200BC7305 /* SwiftLintXcode.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04E4BF351CB25D3200BC7305 /* SwiftLintXcode.swift */; };
 		04E4BF381CB25D3200BC7305 /* NSObject_Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04E4BF371CB25D3200BC7305 /* NSObject_Extension.swift */; };
@@ -20,6 +21,7 @@
 		0498717D1CB27F8900C5F7B5 /* SwiftLintXcodeTRVSXcode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = SwiftLintXcodeTRVSXcode.h; sourceTree = "<group>"; };
 		0498717E1CB27F8900C5F7B5 /* SwiftLintXcodeTRVSXcode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = SwiftLintXcodeTRVSXcode.m; sourceTree = "<group>"; };
 		049871801CB28EBF00C5F7B5 /* Formatter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Formatter.swift; sourceTree = "<group>"; };
+		04DFAD481CB50BC8007998DF /* errorHelper.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = errorHelper.swift; sourceTree = "<group>"; };
 		04E4BF2F1CB25D3100BC7305 /* SwiftLintXcode.xcplugin */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = SwiftLintXcode.xcplugin; sourceTree = BUILT_PRODUCTS_DIR; };
 		04E4BF331CB25D3200BC7305 /* SwiftLintXcode.xcscheme */ = {isa = PBXFileReference; lastKnownFileType = text.xml; name = SwiftLintXcode.xcscheme; path = SwiftLintXcode.xcodeproj/xcshareddata/xcschemes/SwiftLintXcode.xcscheme; sourceTree = SOURCE_ROOT; };
 		04E4BF351CB25D3200BC7305 /* SwiftLintXcode.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SwiftLintXcode.swift; sourceTree = "<group>"; };
@@ -54,6 +56,7 @@
 				04E4BF371CB25D3200BC7305 /* NSObject_Extension.swift */,
 				04E4BF401CB273A700BC7305 /* SaveHook.swift */,
 				049871801CB28EBF00C5F7B5 /* Formatter.swift */,
+				04DFAD481CB50BC8007998DF /* errorHelper.swift */,
 				04E4BF391CB25D3200BC7305 /* Info.plist */,
 				04E4BF321CB25D3200BC7305 /* Supporting Files */,
 				0498717C1CB27F8800C5F7B5 /* SwiftLintXcode-Bridging-Header.h */,
@@ -139,6 +142,7 @@
 				0498717F1CB27F8900C5F7B5 /* SwiftLintXcodeTRVSXcode.m in Sources */,
 				04E4BF361CB25D3200BC7305 /* SwiftLintXcode.swift in Sources */,
 				049871811CB28EBF00C5F7B5 /* Formatter.swift in Sources */,
+				04DFAD491CB50BC8007998DF /* errorHelper.swift in Sources */,
 				04E4BF411CB273A700BC7305 /* SaveHook.swift in Sources */,
 				04E4BF381CB25D3200BC7305 /* NSObject_Extension.swift in Sources */,
 			);
diff --git a/SwiftLintXcode/Formatter.swift b/SwiftLintXcode/Formatter.swift
index 2de43a8..c8033be 100644
--- a/SwiftLintXcode/Formatter.swift
+++ b/SwiftLintXcode/Formatter.swift
@@ -31,9 +31,7 @@ final class Formatter {
         } catch let error as NSError {
             NSAlert(error: error).runModal()
         } catch {
-            NSAlert(error: NSError(domain: "net.ypresto.SwiftLintXcode", code: 0, userInfo: [
-                NSLocalizedDescriptionKey: "Unknown error occured: \(error)"
-            ])).runModal()
+            NSAlert(error: errorWithMessage("Unknown error occured: \(error)")).runModal()
         }
         return false
     }
@@ -81,9 +79,7 @@ final class Formatter {
             ])
             task.waitUntilExit()
             if task.terminationStatus != 0 {
-                throw NSError(domain: "net.ypresto.SwiftLintXcode", code: 0, userInfo: [
-                    NSLocalizedDescriptionKey: "Executing swiftlint exited with non-zero status."
-                ])
+                throw errorWithMessage("Executing swiftlint exited with non-zero status.")
             }
             return try String(contentsOfFile: filePath, encoding: NSUTF8StringEncoding)
         }
@@ -100,22 +96,16 @@ final class Formatter {
         task.launch()
         task.waitUntilExit()
         if task.terminationStatus != 0 {
-            throw NSError(domain: "net.ypresto.SwiftLintXcode", code: 0, userInfo: [
-                NSLocalizedDescriptionKey: "Executing `which swiftlint` exited with non-zero status."
-            ])
+            throw errorWithMessage("Executing `which swiftlint` exited with non-zero status.")
         }
 
         let data = pipe.fileHandleForReading.readDataToEndOfFile()
         guard let pathString = String(data: data, encoding: NSUTF8StringEncoding) else {
-            throw NSError(domain: "net.ypresto.SwiftLintXcode", code: 0, userInfo: [
-                NSLocalizedDescriptionKey: "Cannot read result of `which swiftlint`."
-            ])
+            throw errorWithMessage("Cannot read result of `which swiftlint`.")
         }
         let path = pathString.stringByTrimmingCharactersInSet(NSCharacterSet.newlineCharacterSet())
         if !fileManager.isExecutableFileAtPath(path) {
-            throw NSError(domain: "net.ypresto.SwiftLintXcode", code: 0, userInfo: [
-                NSLocalizedDescriptionKey: "swiftlint at \(path) is not executable."
-            ])
+            throw errorWithMessage("swiftlint at \(path) is not executable.")
         }
         return path
     }
@@ -123,9 +113,7 @@ final class Formatter {
     private func withTempporaryFile<T>(@noescape callback: (filePath: String) throws -> T) throws -> T {
         let filePath = createTemporaryPath()
         if fileManager.fileExistsAtPath(filePath) {
-            throw NSError(domain: "net.ypresto.SwiftLintXcode", code: 0, userInfo: [
-                NSLocalizedDescriptionKey: "Cannot write to \(filePath), file already exists."
-            ])
+            throw errorWithMessage("Cannot write to \(filePath), file already exists.")
         }
         defer { _ = try? fileManager.removeItemAtPath(filePath) }
         return try callback(filePath: filePath)
diff --git a/SwiftLintXcode/errorHelper.swift b/SwiftLintXcode/errorHelper.swift
new file mode 100644
index 0000000..3e370b1
--- /dev/null
+++ b/SwiftLintXcode/errorHelper.swift
@@ -0,0 +1,15 @@
+//
+//  errorHelper.swift
+//  SwiftLintXcode
+//
+//  Created by yuya.tanaka on 2016/04/06.
+//  Copyright © 2016年 Yuya Tanaka. All rights reserved.
+//
+
+import Foundation
+
+func errorWithMessage(message: String) -> NSError {
+    return NSError(domain: "net.ypresto.SwiftLintXcode", code: 0, userInfo: [
+        NSLocalizedDescriptionKey: message
+    ])
+}