diff --git a/.travis.yml b/.travis.yml
index 03152f1..f8e62cc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
-osx_image: xcode10
+osx_image: xcode10.2
 language: swift
 cache:
   directories:
@@ -18,7 +18,7 @@ after_deploy:
 - pod trunk push --skip-import-validation --skip-tests --allow-warnings
 script:
 - set -o pipefail && xcodebuild test -scheme Base58Swift -destination 'platform=iOS
-  Simulator,name=iPhone XS,OS=12.0' ONLY_ACTIVE_ARCH=YES | xcpretty
+  Simulator,name=iPhone XS,OS=12.2' ONLY_ACTIVE_ARCH=YES | xcpretty
 after_success:
 - slather
 - bash <(curl -s https://codecov.io/bash)
diff --git a/Base58Swift.podspec b/Base58Swift.podspec
index 7103bb7..6087728 100644
--- a/Base58Swift.podspec
+++ b/Base58Swift.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name         = "Base58Swift"
-  s.version      = "1.1.0"
+  s.version      = "2.0.0"
   s.summary      = "A pure swift implementation of base58 string encoding and decoding."
   s.description  = <<-DESC
   A pure swift implementation of base58 string encoding and decoding. Based off of https://github.com/jbenet/go-base58.
@@ -9,7 +9,7 @@ Pod::Spec.new do |s|
   s.homepage      = "https://github.com/keefertaylor/Base58Swift"
   s.license       = { :type => "MIT", :file => "LICENSE" }
   s.author        = { "Keefer Taylor" => "keefer@keefertaylor.com" }
-  s.source        = { :git => "https://github.com/keefertaylor/Base58Swift.git", :tag => "1.1.0" }
+  s.source        = { :git => "https://github.com/keefertaylor/Base58Swift.git", :tag => "2.0.0" }
   s.source_files  = "Base58Swift/*.swift"
   s.swift_version = "4.2"
   s.ios.deployment_target = "8.0"
diff --git a/Base58Swift.xcodeproj/project.pbxproj b/Base58Swift.xcodeproj/project.pbxproj
index 4d41c64..c92a51f 100644
--- a/Base58Swift.xcodeproj/project.pbxproj
+++ b/Base58Swift.xcodeproj/project.pbxproj
@@ -165,11 +165,11 @@
 				TargetAttributes = {
 					770DFBF42214CD2F00E8E70A = {
 						CreatedOnToolsVersion = 10.1;
-						LastSwiftMigration = 1010;
+						LastSwiftMigration = 1020;
 					};
 					770DFBFD2214CD2F00E8E70A = {
 						CreatedOnToolsVersion = 10.1;
-						LastSwiftMigration = 1010;
+						LastSwiftMigration = 1020;
 					};
 				};
 			};
@@ -428,7 +428,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Debug;
@@ -459,7 +459,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = com.keefertaylor.Base58Swift;
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Release;
@@ -480,7 +480,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = com.keefertaylor.Base58SwiftTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Debug;
@@ -500,7 +500,7 @@
 				);
 				PRODUCT_BUNDLE_IDENTIFIER = com.keefertaylor.Base58SwiftTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Release;
diff --git a/Base58Swift/Base58.swift b/Base58Swift/Base58.swift
index 98d3b3a..6c1df1e 100644
--- a/Base58Swift/Base58.swift
+++ b/Base58Swift/Base58.swift
@@ -68,7 +68,7 @@ public enum Base58 {
     let byteString = [UInt8](input.utf8)
 
     for char in byteString.reversed() {
-      guard let alphabetIndex = alphabet.index(of: char) else {
+      guard let alphabetIndex = alphabet.firstIndex(of: char) else {
         return nil
       }
       answer += (i * BigUInt(alphabetIndex))