diff --git a/CharacterGenerator/CharacterGenerator.xcodeproj/project.pbxproj b/CharacterGenerator/CharacterGenerator.xcodeproj/project.pbxproj
index 17ce60d..dd02186 100644
--- a/CharacterGenerator/CharacterGenerator.xcodeproj/project.pbxproj
+++ b/CharacterGenerator/CharacterGenerator.xcodeproj/project.pbxproj
@@ -298,16 +298,16 @@
 				TargetAttributes = {
 					B621A3A21F0C1C7400E55236 = {
 						CreatedOnToolsVersion = 9.0;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 					};
 					B621A3B81F0C1C7500E55236 = {
 						CreatedOnToolsVersion = 9.0;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 						TestTargetID = B621A3A21F0C1C7400E55236;
 					};
 					B6C87F3F1F83CD3E007CB209 = {
 						CreatedOnToolsVersion = 9.0;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 						ProvisioningStyle = Automatic;
 						TestTargetID = B621A3A21F0C1C7400E55236;
 					};
@@ -558,7 +558,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.CharacterGenerator;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Debug;
@@ -572,7 +572,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.CharacterGenerator;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 			};
 			name = Release;
@@ -587,7 +587,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.CharacterGeneratorTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/CharacterGenerator.app/CharacterGenerator";
 			};
@@ -603,7 +603,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.CharacterGeneratorTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_HOST = "$(BUILT_PRODUCTS_DIR)/CharacterGenerator.app/CharacterGenerator";
 			};
@@ -620,7 +620,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.CharacterGeneratorUITests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_TARGET_NAME = CharacterGenerator;
 			};
@@ -637,7 +637,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.CharacterGeneratorUITests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 				TARGETED_DEVICE_FAMILY = "1,2";
 				TEST_TARGET_NAME = CharacterGenerator;
 			};
diff --git a/CharacterGenerator/CharacterGenerator/Configuration/Currencies.json b/CharacterGenerator/CharacterGenerator/Configuration/Currencies.json
index 9ce0210..fc5e296 100644
--- a/CharacterGenerator/CharacterGenerator/Configuration/Currencies.json
+++ b/CharacterGenerator/CharacterGenerator/Configuration/Currencies.json
@@ -20,7 +20,7 @@
                  },
                  {
                  "symbol": "gp",
-                 "default": true,
+                 "is default": true,
                  "coefficient": 1.0,
                  "name": "gold piece",
                  "plural": "gold pieces"
diff --git a/RolePlayingCore/RolePlayingCore.xcodeproj/project.pbxproj b/RolePlayingCore/RolePlayingCore.xcodeproj/project.pbxproj
index 60b4346..df9a511 100644
--- a/RolePlayingCore/RolePlayingCore.xcodeproj/project.pbxproj
+++ b/RolePlayingCore/RolePlayingCore.xcodeproj/project.pbxproj
@@ -380,13 +380,13 @@
 				TargetAttributes = {
 					B62055ED1E19DD23002494AB = {
 						CreatedOnToolsVersion = 8.2.1;
-						LastSwiftMigration = 1000;
+						LastSwiftMigration = 1020;
 						ProvisioningStyle = Automatic;
 					};
 					B62055F61E19DD23002494AB = {
 						CreatedOnToolsVersion = 8.2.1;
 						DevelopmentTeam = J69E69SP27;
-						LastSwiftMigration = "";
+						LastSwiftMigration = 1020;
 						ProvisioningStyle = Automatic;
 					};
 				};
@@ -649,7 +649,7 @@
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -669,7 +669,7 @@
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.RolePlayingCore;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SKIP_INSTALL = YES;
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
@@ -682,7 +682,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.RolePlayingCoreTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Debug;
 		};
@@ -695,7 +695,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks @loader_path/Frameworks";
 				PRODUCT_BUNDLE_IDENTIFIER = com.flatearthstudio.RolePlayingCoreTests;
 				PRODUCT_NAME = "$(TARGET_NAME)";
-				SWIFT_VERSION = 4.2;
+				SWIFT_VERSION = 5.0;
 			};
 			name = Release;
 		};
diff --git a/RolePlayingCore/RolePlayingCore/Currency/Currencies.swift b/RolePlayingCore/RolePlayingCore/Currency/Currencies.swift
index 9df6288..85cc190 100644
--- a/RolePlayingCore/RolePlayingCore/Currency/Currencies.swift
+++ b/RolePlayingCore/RolePlayingCore/Currency/Currencies.swift
@@ -8,14 +8,30 @@
 
 public struct Currencies {
     
-    /// An array of all currently loaded currencies.
-    public static var allCurrencies: [UnitCurrency] = []
+    /// A map of all currently loaded currencies.
+    internal static var allCurrencies: [String: UnitCurrency] = [:]
     
-    /// Looks up the currency instance that matches the specified symbol.
-    /// Returns nil if the symbol isn't found.
+    /// Returns the unit currency corresponding to this symbol. Returns nil if no symbol matches.
     public static func find(_ symbol: String) -> UnitCurrency? {
-        return allCurrencies.first(where: { $0.symbol == symbol })
+        return Currencies.allCurrencies[symbol]
     }
+  
+    public static func add(_ currency: UnitCurrency) {
+        allCurrencies[currency.symbol] = currency
+    }
+
+    public static func setDefault(_ newBaseUnit: UnitCurrency) {
+        // Remove the old base unit from all currencies.
+        let oldSymbol = UnitCurrency.baseUnitCurrency.symbol
+        guard oldSymbol != newBaseUnit.symbol else {
+            return
+        }
+        
+        allCurrencies[oldSymbol] = nil
+        
+        UnitCurrency.baseUnitCurrency = newBaseUnit
+    }
+    
 }
 
 extension Currencies: Codable {
@@ -27,14 +43,34 @@ extension Currencies: Codable {
         let coefficient: Double
         let name: String
         let plural: String
-        let `default`: Bool? // TODO: this is fishy
+        let isDefault: Bool
+        
+        private enum CodingKeys: String, CodingKey {
+            case symbol
+            case coefficient
+            case name
+            case plural
+            case isDefault = "is default"
+        }
         
+        // For writing
         init(_ unitCurrency: UnitCurrency) {
             self.symbol = unitCurrency.symbol
             self.coefficient = (unitCurrency.converter as! UnitConverterLinear).coefficient
             self.name = unitCurrency.name
             self.plural = unitCurrency.plural
-            self.default = unitCurrency == .baseUnit()
+            self.isDefault = unitCurrency == .baseUnit()
+        }
+        
+        // For reading
+        init(from decoder: Decoder) throws {
+            let container = try decoder.container(keyedBy: CodingKeys.self)
+
+            symbol = try container.decode(String.self, forKey: .symbol)
+            coefficient = try container.decode(Double.self, forKey: .coefficient)
+            name = try container.decode(String.self, forKey: .name)
+            plural = try container.decode(String.self, forKey: .plural)
+            isDefault = try container.decodeIfPresent(Bool.self, forKey: .isDefault) ?? false
         }
     }
     
@@ -48,14 +84,13 @@ extension Currencies: Codable {
         
         let currencies = try container.decode([Currency].self, forKey: .currencies)
         for currency in currencies {
-            if Currencies.find(currency.symbol) == nil {
-                let converter = UnitConverterLinear(coefficient: currency.coefficient)
-                let unitCurrency = UnitCurrency(symbol: currency.symbol, converter: converter, name: currency.name, plural: currency.plural)
-                Currencies.allCurrencies.append(unitCurrency)
-                
-                if currency.default != nil, currency.default! {
-                    UnitCurrency.default = unitCurrency
-                }
+            let converter = UnitConverterLinear(coefficient: currency.coefficient)
+            let unitCurrency = UnitCurrency(symbol: currency.symbol, converter: converter, name: currency.name, plural: currency.plural)
+            
+            Currencies.add(unitCurrency)
+            
+            if currency.isDefault {
+                Currencies.setDefault(unitCurrency)
             }
         }
     }
@@ -64,7 +99,7 @@ extension Currencies: Codable {
         var container = encoder.container(keyedBy: CodingKeys.self)
         
         var currencies = [Currency]()
-        for unitCurrency in Currencies.allCurrencies {
+        for unitCurrency in Currencies.allCurrencies.values {
             let currency = Currency(unitCurrency)
             currencies.append(currency)
         }
diff --git a/RolePlayingCore/RolePlayingCore/Currency/Money.swift b/RolePlayingCore/RolePlayingCore/Currency/Money.swift
index fbb654c..860d457 100644
--- a/RolePlayingCore/RolePlayingCore/Currency/Money.swift
+++ b/RolePlayingCore/RolePlayingCore/Currency/Money.swift
@@ -18,7 +18,7 @@ public extension String {
         var value: Double?
         var unit: UnitCurrency = .baseUnit()
         
-        for currency in Currencies.allCurrencies {
+        for currency in Currencies.allCurrencies.values {
             if let range = self.range(of: currency.symbol), range.upperBound == self.endIndex {
                 value = Double(self[..<range.lowerBound].trimmingCharacters(in: .whitespaces))!
                 unit = currency
diff --git a/RolePlayingCore/RolePlayingCore/Currency/UnitCurrency.swift b/RolePlayingCore/RolePlayingCore/Currency/UnitCurrency.swift
index 967ec4e..d1636a1 100644
--- a/RolePlayingCore/RolePlayingCore/Currency/UnitCurrency.swift
+++ b/RolePlayingCore/RolePlayingCore/Currency/UnitCurrency.swift
@@ -11,7 +11,7 @@ import Foundation
 /// Units of currency or coinage.
 ///
 /// Use `Measurement<UnitCurrency>` to hold values of currency.
-public class UnitCurrency : Dimension {
+public final class UnitCurrency : Dimension {
     
     /// The singular unit name used when the unitStyle is long.
     public internal(set) var name: String!
@@ -19,13 +19,11 @@ public class UnitCurrency : Dimension {
     /// The plural unit name used when the unitStyle is long.
     public internal(set) var plural: String!
     
-    /// The default unit currency. Set during load().
-    public internal(set) static var `default`: UnitCurrency?
+    /// The default base unit is a currency called "credit". It may be replaced at runtime.
+    internal static var baseUnitCurrency = UnitCurrency(symbol: "c", converter: UnitConverterLinear(coefficient: 1.0), name: "credit", plural: "credits")
     
-    /// Returns the default unit currency. Will unwrap nil if load() hasn't been called,
-    /// or if none of the loaded currencies was marked default.
     public override class func baseUnit() -> UnitCurrency {
-        return UnitCurrency.default!
+        return baseUnitCurrency
     }
     
     public init(symbol: String, converter: UnitConverter, name: String, plural: String) {
diff --git a/RolePlayingCore/RolePlayingCore/Dice/DiceParser.swift b/RolePlayingCore/RolePlayingCore/Dice/DiceParser.swift
index c03680f..185b353 100644
--- a/RolePlayingCore/RolePlayingCore/Dice/DiceParser.swift
+++ b/RolePlayingCore/RolePlayingCore/Dice/DiceParser.swift
@@ -243,7 +243,7 @@ public extension String {
     /// - returns: Dice representing the parsed string. Returns `nil` if the string
     ///   could not be interpreted; for example, if there are extraneous
     ///   characters, or an unsupported dice such as d7 is specified.
-    public var parseDice: Dice? {
+    var parseDice: Dice? {
         var dice: Dice? = nil
         
         do {
@@ -269,7 +269,7 @@ public extension KeyedDecodingContainer  {
     /// See `String.parseDice` for supported string formats.
     ///
     /// - throws `DecodingError.dataCorrupted` if the dice is not present or could not be decoded.
-    public func decode(_ type: Dice.Protocol, forKey key: K) throws -> Dice {
+    func decode(_ type: Dice.Protocol, forKey key: K) throws -> Dice {
         let dice: Dice?
         
         if let number = try? self.decode(Int.self, forKey: key) {
@@ -291,7 +291,7 @@ public extension KeyedDecodingContainer  {
     /// See `String.parseDice` for supported string formats.
     ///
     /// - throws `DecodingError.dataCorrupted` if the dice could not be decoded.
-    public func decodeIfPresent(_ type: Dice.Protocol, forKey key: K) throws -> Dice? {
+    func decodeIfPresent(_ type: Dice.Protocol, forKey key: K) throws -> Dice? {
         let dice: Dice?
         
         if let number = try? self.decode(Int.self, forKey: key) {
diff --git a/RolePlayingCore/RolePlayingCore/Player/Alignment.swift b/RolePlayingCore/RolePlayingCore/Player/Alignment.swift
index 3e0b933..0ec8f01 100644
--- a/RolePlayingCore/RolePlayingCore/Player/Alignment.swift
+++ b/RolePlayingCore/RolePlayingCore/Player/Alignment.swift
@@ -217,9 +217,8 @@ extension Alignment: Codable {
             // The value must decode into either two doubles or two strings with the coding keys.
             let values = try decoder.container(keyedBy: CodingKeys.self)
             if let ethicsValue = try? values.decodeIfPresent(Double.self, forKey: .ethics),
-                let moralsValue = try? values.decodeIfPresent(Double.self, forKey: .morals),
-                ethicsValue != nil && moralsValue != nil {
-                self.init(ethics: ethicsValue!, morals: moralsValue!)
+                let moralsValue = try? values.decodeIfPresent(Double.self, forKey: .morals) {
+                self.init(ethics: ethicsValue, morals: moralsValue)
             } else {
                 let ethics = try values.decode(Ethics.self, forKey: .ethics)
                 let morals = try values.decode(Morals.self, forKey: .morals)
diff --git a/RolePlayingCore/RolePlayingCore/Player/Player.swift b/RolePlayingCore/RolePlayingCore/Player/Player.swift
index 9fe7312..5799137 100644
--- a/RolePlayingCore/RolePlayingCore/Player/Player.swift
+++ b/RolePlayingCore/RolePlayingCore/Player/Player.swift
@@ -11,7 +11,7 @@ import Foundation
 public extension AbilityScores {
     
     // Sets the ability scores to random values using 4d6-L
-    public mutating func roll() {
+    mutating func roll() {
         let dice = DroppingDice(.d6, times: 4, drop: .lowest)
         for ability in abilities {
             scores[ability] = dice.roll().result
diff --git a/RolePlayingCore/RolePlayingCoreTests/CurrencyTests.swift b/RolePlayingCore/RolePlayingCoreTests/CurrencyTests.swift
index e1ed243..6b305eb 100644
--- a/RolePlayingCore/RolePlayingCoreTests/CurrencyTests.swift
+++ b/RolePlayingCore/RolePlayingCoreTests/CurrencyTests.swift
@@ -8,7 +8,7 @@
 
 import XCTest
 
-import RolePlayingCore
+@testable import RolePlayingCore
 
 
 class UnitCurrencyTests: XCTestCase {
diff --git a/RolePlayingCore/RolePlayingCoreTests/TestCurrencies.json b/RolePlayingCore/RolePlayingCoreTests/TestCurrencies.json
index 9a5486d..723f244 100644
--- a/RolePlayingCore/RolePlayingCoreTests/TestCurrencies.json
+++ b/RolePlayingCore/RolePlayingCoreTests/TestCurrencies.json
@@ -2,7 +2,7 @@
     "currencies": [
                  {
                  "symbol": "gp",
-                 "default": true,
+                 "is default": true,
                  "coefficient": 1.0,
                  "name": "gold piece",
                  "plural": "gold pieces"