diff --git a/.swift-version b/.swift-version
index 9f55b2c..5186d07 100644
--- a/.swift-version
+++ b/.swift-version
@@ -1 +1 @@
-3.0
+4.0
diff --git a/.travis.yml b/.travis.yml
index f645ba9..7d3835a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
-osx_image: xcode8
+osx_image: xcode9
 language: objective-c
 script:
 # iOS Static Lib
diff --git a/ZipUtilities.xcodeproj/project.pbxproj b/ZipUtilities.xcodeproj/project.pbxproj
index a5d5efd..c86e655 100644
--- a/ZipUtilities.xcodeproj/project.pbxproj
+++ b/ZipUtilities.xcodeproj/project.pbxproj
@@ -2483,7 +2483,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OBJC_BRIDGING_HEADER = "ZipUtilitiesTests/FrameworkTests-Bridging-Header.h";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -2499,7 +2499,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "com.NSProgrammer.$(PRODUCT_NAME:rfc1034identifier)";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OBJC_BRIDGING_HEADER = "ZipUtilitiesTests/FrameworkTests-Bridging-Header.h";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};
@@ -2577,7 +2577,7 @@
 				SDKROOT = macosx;
 				SWIFT_OBJC_BRIDGING_HEADER = "ZipUtilitiesTests/OSXFrameworkTests-Bridging-Header.h";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Debug;
 		};
@@ -2598,7 +2598,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = macosx;
 				SWIFT_OBJC_BRIDGING_HEADER = "ZipUtilitiesTests/OSXFrameworkTests-Bridging-Header.h";
-				SWIFT_VERSION = 3.0;
+				SWIFT_VERSION = 4.0;
 			};
 			name = Release;
 		};