diff --git a/.swiftlint.yml b/.swiftlint.yml
index 0a0becd..953de4d 100644
--- a/.swiftlint.yml
+++ b/.swiftlint.yml
@@ -3,6 +3,7 @@ disabled_rules:
   - force_cast
   - force_try
   - function_body_length
+  - identifier_name
   - type_body_length
 
 opt_in_rules:
@@ -12,7 +13,9 @@ opt_in_rules:
   - conditional_returns_on_newline
   - empty_count
   - explicit_init
+  - fatal_error_message
   - first_where
+  - implicitly_unwrapped_optional
   - overridden_super_call
   - private_outlet
   - prohibited_super_call
diff --git a/.travis.yml b/.travis.yml
index 503adb8..cdefe09 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: objective-c
 
-osx_image: xcode8.2
+osx_image: xcode8.3
 
 sudo: false # Enable container-based builds
 
diff --git a/SwiftGit2.xcodeproj/project.pbxproj b/SwiftGit2.xcodeproj/project.pbxproj
index c9144e7..5690abf 100644
--- a/SwiftGit2.xcodeproj/project.pbxproj
+++ b/SwiftGit2.xcodeproj/project.pbxproj
@@ -729,7 +729,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "if which swiftlint >/dev/null; then\n    swiftlint\nelse\n    echo \"warning: SwiftLint is not installed\"\nfi";
+			shellScript = "if which swiftlint >/dev/null; then\n    swiftlint --lenient\nelse\n    echo \"warning: SwiftLint is not installed\"\nfi";
 		};
 /* End PBXShellScriptBuildPhase section */
 
@@ -1180,6 +1180,7 @@
 				C9CE0DD51E0710BD0053205D /* Release */,
 			);
 			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
 		};
 /* End XCConfigurationList section */
 	};
diff --git a/SwiftGit2/Repository.swift b/SwiftGit2/Repository.swift
index 2c20389..ea08a08 100644
--- a/SwiftGit2/Repository.swift
+++ b/SwiftGit2/Repository.swift
@@ -15,7 +15,7 @@ public typealias CheckoutProgressBlock = (String?, Int, Int) -> Void
 /// Helper function used as the libgit2 progress callback in git_checkout_options.
 /// This is a function with a type signature of git_checkout_progress_cb.
 private func checkoutProgressCallback(path: UnsafePointer<Int8>?, completedSteps: Int, totalSteps: Int,
-                                      payload: UnsafeMutableRawPointer?) -> Void {
+                                      payload: UnsafeMutableRawPointer?) {
 	if let payload = payload {
 		let buffer = payload.assumingMemoryBound(to: CheckoutProgressBlock.self)
 		let block: CheckoutProgressBlock