diff --git a/.travis.yml b/.travis.yml
index e97d495..51ceee2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,7 @@
 language: objective-c
 
 os: osx
-osx_image: xcode9
+osx_image: xcode10.2
 
 env:
   global:
diff --git a/PySwiftyRegex.xcodeproj/project.pbxproj b/PySwiftyRegex.xcodeproj/project.pbxproj
index c9bf6c2..164bd0e 100644
--- a/PySwiftyRegex.xcodeproj/project.pbxproj
+++ b/PySwiftyRegex.xcodeproj/project.pbxproj
@@ -160,11 +160,11 @@
 				TargetAttributes = {
 					0CEBDD231B39B8C3003A40BB = {
 						CreatedOnToolsVersion = 7.0;
-						LastSwiftMigration = 0900;
+						LastSwiftMigration = 1020;
 					};
 					0CEBDD2C1B39B8C4003A40BB = {
 						CreatedOnToolsVersion = 7.0;
-						LastSwiftMigration = 0900;
+						LastSwiftMigration = 1020;
 					};
 				};
 			};
@@ -173,6 +173,7 @@
 			developmentRegion = English;
 			hasScannedForEncodings = 0;
 			knownRegions = (
+				English,
 				en,
 			);
 			mainGroup = 0CEBDCD41B39B2FB003A40BB;
@@ -360,7 +361,7 @@
 				MACH_O_TYPE = mh_dylib;
 				MACOSX_DEPLOYMENT_TARGET = 10.9;
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -380,7 +381,7 @@
 				MACOSX_DEPLOYMENT_TARGET = 10.9;
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
@@ -395,7 +396,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = "me.cezheng.PySwiftyRegex-OSXTests";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = macosx;
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -411,7 +412,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = macosx;
 				SWIFT_OPTIMIZATION_LEVEL = "-Owholemodule";
-				SWIFT_VERSION = 4.0;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
diff --git a/PySwiftyRegex.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist b/PySwiftyRegex.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
new file mode 100644
index 0000000..18d9810
--- /dev/null
+++ b/PySwiftyRegex.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>
diff --git a/PySwiftyRegex/PySwiftyRegex.swift b/PySwiftyRegex/PySwiftyRegex.swift
index cfb29ab..ca037ef 100644
--- a/PySwiftyRegex/PySwiftyRegex.swift
+++ b/PySwiftyRegex/PySwiftyRegex.swift
@@ -271,7 +271,7 @@ public class re {
           return
         }
         
-        end = string.characters.index(string.startIndex, offsetBy: result.range.location)
+        end = string.index(string.startIndex, offsetBy: result.range.location)
         results.append(String(string[start..<end]))
         if regex.numberOfCaptureGroups > 0 {
           results += MatchObject(string: string, match: result).groups()