diff --git a/Sources/XMLParsing/Decoder/DecodingErrorExtension.swift b/Sources/XMLParsing/Decoder/DecodingErrorExtension.swift
index d82e005..fdd8f80 100644
--- a/Sources/XMLParsing/Decoder/DecodingErrorExtension.swift
+++ b/Sources/XMLParsing/Decoder/DecodingErrorExtension.swift
@@ -19,7 +19,7 @@ internal extension DecodingError {
     /// - parameter expectation: The type expected to be encountered.
     /// - parameter reality: The value that was encountered instead of the expected type.
     /// - returns: A `DecodingError` with the appropriate path and debug description.
-    internal static func _typeMismatch(at path: [CodingKey], expectation: Any.Type, reality: Any) -> DecodingError {
+    static func _typeMismatch(at path: [CodingKey], expectation: Any.Type, reality: Any) -> DecodingError {
         let description = "Expected to decode \(expectation) but found \(_typeDescription(of: reality)) instead."
         return .typeMismatch(expectation, Context(codingPath: path, debugDescription: description))
     }
@@ -29,7 +29,7 @@ internal extension DecodingError {
     /// - parameter value: The value whose type to describe.
     /// - returns: A string describing `value`.
     /// - precondition: `value` is one of the types below.
-    internal static func _typeDescription(of value: Any) -> String {
+    static func _typeDescription(of value: Any) -> String {
         if value is NSNull {
             return "a null value"
         } else if value is NSNumber /* FIXME: If swift-corelibs-foundation isn't updated to use NSNumber, this check will be necessary: || value is Int || value is Double */ {
diff --git a/Sources/XMLParsing/Decoder/XMLDecoder.swift b/Sources/XMLParsing/Decoder/XMLDecoder.swift
index 1602d85..50b6cac 100644
--- a/Sources/XMLParsing/Decoder/XMLDecoder.swift
+++ b/Sources/XMLParsing/Decoder/XMLDecoder.swift
@@ -129,7 +129,7 @@ open class XMLDecoder {
             guard !stringKey.isEmpty else { return stringKey }
             
             // Find the first non-underscore character
-            guard let firstNonUnderscore = stringKey.index(where: { $0 != "_" }) else {
+            guard let firstNonUnderscore = stringKey.firstIndex(where: { $0 != "_" }) else {
                 // Reached the end without finding an _
                 return stringKey
             }
diff --git a/Sources/XMLParsing/Encoder/EncodingErrorExtension.swift b/Sources/XMLParsing/Encoder/EncodingErrorExtension.swift
index 70cb140..c9720f5 100644
--- a/Sources/XMLParsing/Encoder/EncodingErrorExtension.swift
+++ b/Sources/XMLParsing/Encoder/EncodingErrorExtension.swift
@@ -18,7 +18,7 @@ internal extension EncodingError {
     /// - parameter value: The value that was invalid to encode.
     /// - parameter path: The path of `CodingKey`s taken to encode this value.
     /// - returns: An `EncodingError` with the appropriate path and debug description.
-    internal static func _invalidFloatingPointValue<T : FloatingPoint>(_ value: T, at codingPath: [CodingKey]) -> EncodingError {
+    static func _invalidFloatingPointValue<T : FloatingPoint>(_ value: T, at codingPath: [CodingKey]) -> EncodingError {
         let valueDescription: String
         if value == T.infinity {
             valueDescription = "\(T.self).infinity"
diff --git a/XMLParsing.xcodeproj/project.pbxproj b/XMLParsing.xcodeproj/project.pbxproj
index c0d74c5..14c354e 100644
--- a/XMLParsing.xcodeproj/project.pbxproj
+++ b/XMLParsing.xcodeproj/project.pbxproj
@@ -131,7 +131,7 @@
 			name = Products;
 			sourceTree = BUILT_PRODUCTS_DIR;
 		};
-		OBJ_5 /*  */ = {
+		OBJ_5 = {
 			isa = PBXGroup;
 			children = (
 				OBJ_6 /* Package.swift */,
@@ -140,7 +140,6 @@
 				OBJ_26 /* Sample XML */,
 				OBJ_27 /* Products */,
 			);
-			name = "";
 			sourceTree = "<group>";
 		};
 		OBJ_7 /* Sources */ = {
@@ -235,10 +234,10 @@
 				LastUpgradeCheck = 9999;
 				TargetAttributes = {
 					"XMLParsing::XMLParsing" = {
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 					};
 					"XMLParsing::XMLParsingTests" = {
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 					};
 				};
 			};
@@ -247,9 +246,10 @@
 			developmentRegion = English;
 			hasScannedForEncodings = 0;
 			knownRegions = (
+				English,
 				en,
 			);
-			mainGroup = OBJ_5 /*  */;
+			mainGroup = OBJ_5;
 			productRefGroup = OBJ_27 /* Products */;
 			projectDirPath = "";
 			projectRoot = "";
@@ -367,7 +367,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../Frameworks @loader_path/Frameworks";
 				OTHER_LDFLAGS = "$(inherited)";
 				OTHER_SWIFT_FLAGS = "$(inherited)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGET_NAME = XMLParsingTests;
 			};
 			name = Debug;
@@ -385,7 +385,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "@loader_path/../Frameworks @loader_path/Frameworks";
 				OTHER_LDFLAGS = "$(inherited)";
 				OTHER_SWIFT_FLAGS = "$(inherited)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGET_NAME = XMLParsingTests;
 			};
 			name = Release;
@@ -427,7 +427,7 @@
 				PRODUCT_MODULE_NAME = "$(TARGET_NAME:c99extidentifier)";
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGET_NAME = XMLParsing;
 			};
 			name = Debug;
@@ -449,7 +449,7 @@
 				PRODUCT_MODULE_NAME = "$(TARGET_NAME:c99extidentifier)";
 				PRODUCT_NAME = "$(TARGET_NAME:c99extidentifier)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGET_NAME = XMLParsing;
 			};
 			name = Release;