diff --git a/AltStore/Base.lproj/Main.storyboard b/AltStore/Base.lproj/Main.storyboard
index 5b56a87b..d7d95276 100644
--- a/AltStore/Base.lproj/Main.storyboard
+++ b/AltStore/Base.lproj/Main.storyboard
@@ -1,11 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="16097.2" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="wKh-xq-NuP">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17503.1" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES" initialViewController="wKh-xq-NuP">
     <device id="retina4_7" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="16087"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17502"/>
         <capability name="Named colors" minToolsVersion="9.0"/>
         <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="System colors in document resources" minToolsVersion="11.0"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <scenes>
@@ -16,8 +17,8 @@
                     <view key="view" contentMode="scaleToFill" id="G9E-Qs-gFM">
                         <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
-                        <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                         <viewLayoutGuide key="safeArea" id="sZd-sc-Bvn"/>
+                        <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                     </view>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="vOq-mm-rY5" userLabel="First Responder" sceneMemberID="firstResponder"/>
@@ -72,6 +73,9 @@
                             </connections>
                         </barButtonItem>
                     </navigationItem>
+                    <connections>
+                        <outlet property="sourcesBarButtonItem" destination="6Ul-JW-TMT" id="99s-O4-OpX"/>
+                    </connections>
                 </collectionViewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="cMN-i4-Bxk" userLabel="First Responder" sceneMemberID="firstResponder"/>
             </objects>
@@ -151,7 +155,7 @@
                                                         <rect key="frame" x="0.0" y="0.0" width="18" height="18"/>
                                                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                                         <subviews>
-                                                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="mkD-3C-WMV">
+                                                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="mkD-3C-WMV">
                                                                 <rect key="frame" x="0.0" y="0.0" width="18" height="18"/>
                                                                 <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                                                 <state key="normal" image="Back"/>
@@ -172,6 +176,7 @@
                                 </subviews>
                             </view>
                         </subviews>
+                        <viewLayoutGuide key="safeArea" id="wiR-52-nwg"/>
                         <color key="backgroundColor" name="Background"/>
                         <constraints>
                             <constraint firstItem="Ci9-Iw-aR2" firstAttribute="top" secondItem="0cR-li-tCB" secondAttribute="top" id="015-fz-v3B"/>
@@ -183,11 +188,10 @@
                             <constraint firstAttribute="trailing" secondItem="Qlg-m3-lXg" secondAttribute="trailing" id="UrQ-oK-TKQ"/>
                             <constraint firstAttribute="bottom" secondItem="Qlg-m3-lXg" secondAttribute="bottom" id="Vf7-Fg-88c"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="wiR-52-nwg"/>
                     </view>
                     <navigationItem key="navigationItem" largeTitleDisplayMode="never" id="maq-gT-QcS">
                         <barButtonItem key="rightBarButtonItem" style="plain" id="FLf-DS-F77">
-                            <button key="customView" opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" id="grk-xM-YWA" customClass="PillButton" customModule="AltStore" customModuleProvider="target">
+                            <button key="customView" opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" id="grk-xM-YWA" customClass="PillButton" customModule="AltStore" customModuleProvider="target">
                                 <rect key="frame" x="287" y="6.5" width="72" height="31"/>
                                 <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                                 <color key="backgroundColor" red="0.22352941179999999" green="0.4941176471" blue="0.39607843139999999" alpha="0.10000000000000001" colorSpace="custom" customColorSpace="sRGB"/>
@@ -335,7 +339,7 @@
                                                                     <rect key="frame" x="0.0" y="0.0" width="335" height="0.0"/>
                                                                     <subviews>
                                                                         <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" verticalCompressionResistancePriority="751" text="What's New" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="obM-TM-y2E">
-                                                                            <rect key="frame" x="0.0" y="0.0" width="123.5" height="0.0"/>
+                                                                            <rect key="frame" x="0.0" y="0.0" width="124" height="0.0"/>
                                                                             <fontDescription key="fontDescription" type="boldSystem" pointSize="22"/>
                                                                             <nil key="textColor"/>
                                                                             <nil key="highlightedColor"/>
@@ -426,7 +430,7 @@
                                                                             <stackView verifyAmbiguity="off" opaque="NO" contentMode="scaleToFill" ambiguous="YES" axis="vertical" alignment="center" spacing="6" translatesAutoresizingMaskIntoConstraints="NO" id="fSx-We-L4W">
                                                                                 <rect key="frame" x="0.0" y="0.0" width="56" height="56"/>
                                                                                 <subviews>
-                                                                                    <button opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="79g-9q-mE2">
+                                                                                    <button opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="79g-9q-mE2">
                                                                                         <rect key="frame" x="5" y="0.0" width="50" height="50"/>
                                                                                         <constraints>
                                                                                             <constraint firstAttribute="width" constant="50" id="0LZ-4n-COH"/>
@@ -530,14 +534,14 @@ World</string>
                                 <edgeInsets key="layoutMargins" top="0.0" left="0.0" bottom="0.0" right="0.0"/>
                             </stackView>
                         </subviews>
-                        <color key="backgroundColor" systemColor="tertiarySystemBackgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+                        <viewLayoutGuide key="safeArea" id="c7x-ee-3HH"/>
+                        <color key="backgroundColor" systemColor="tertiarySystemBackgroundColor"/>
                         <constraints>
                             <constraint firstItem="xnC-tS-ZdV" firstAttribute="leading" secondItem="c7x-ee-3HH" secondAttribute="leading" constant="20" id="LO8-Au-SYF"/>
                             <constraint firstItem="c7x-ee-3HH" firstAttribute="bottom" secondItem="xnC-tS-ZdV" secondAttribute="bottom" constant="10" id="NZ9-iG-E10"/>
                             <constraint firstItem="c7x-ee-3HH" firstAttribute="trailing" secondItem="xnC-tS-ZdV" secondAttribute="trailing" constant="20" id="ZkD-tb-mBf"/>
                             <constraint firstItem="xnC-tS-ZdV" firstAttribute="top" secondItem="c7x-ee-3HH" secondAttribute="top" constant="10" id="oKq-9e-DtW"/>
                         </constraints>
-                        <viewLayoutGuide key="safeArea" id="c7x-ee-3HH"/>
                     </view>
                     <connections>
                         <outlet property="descriptionLabel" destination="ErG-8A-uqY" id="iuN-kE-IEm"/>
@@ -686,7 +690,7 @@ World</string>
                                                             <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                                             <subviews>
                                                                 <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="No Updates Available" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="z04-yg-x1t">
-                                                                    <rect key="frame" x="96" y="20" width="167" height="20.5"/>
+                                                                    <rect key="frame" x="96.5" y="20" width="166" height="20.5"/>
                                                                     <fontDescription key="fontDescription" type="system" weight="medium" pointSize="17"/>
                                                                     <color key="textColor" name="Primary"/>
                                                                     <nil key="highlightedColor"/>
@@ -732,16 +736,16 @@ World</string>
                             <autoresizingMask key="autoresizingMask"/>
                             <subviews>
                                 <stackView opaque="NO" contentMode="scaleToFill" horizontalCompressionResistancePriority="900" axis="vertical" translatesAutoresizingMaskIntoConstraints="NO" id="GFQ-Wy-Qhy">
-                                    <rect key="frame" x="138.5" y="0.0" width="98" height="52.5"/>
+                                    <rect key="frame" x="139" y="0.0" width="97" height="52.5"/>
                                     <subviews>
                                         <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="5/10 App IDs" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="LLv-8I-6Of">
-                                            <rect key="frame" x="0.0" y="0.0" width="98" height="20.5"/>
+                                            <rect key="frame" x="0.0" y="0.0" width="97" height="20.5"/>
                                             <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                             <color key="textColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
                                             <nil key="highlightedColor"/>
                                         </label>
-                                        <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="NHb-0F-cHZ">
-                                            <rect key="frame" x="0.0" y="20.5" width="98" height="32"/>
+                                        <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="NHb-0F-cHZ">
+                                            <rect key="frame" x="0.0" y="20.5" width="97" height="32"/>
                                             <fontDescription key="fontDescription" type="system" pointSize="16"/>
                                             <state key="normal" title="View App IDs"/>
                                             <connections>
@@ -788,7 +792,7 @@ World</string>
                     <collectionView key="view" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" preservesSuperviewLayoutMargins="YES" dataMode="prototypes" id="v1r-C8-h6h">
                         <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
-                        <color key="backgroundColor" systemColor="systemBackgroundColor" cocoaTouchSystemColor="whiteColor"/>
+                        <color key="backgroundColor" systemColor="systemBackgroundColor"/>
                         <collectionViewFlowLayout key="collectionViewLayout" minimumLineSpacing="15" minimumInteritemSpacing="10" id="Wzt-qc-XG8">
                             <size key="itemSize" width="375" height="80"/>
                             <size key="headerReferenceSize" width="50" height="60"/>
@@ -848,7 +852,7 @@ World</string>
                             <autoresizingMask key="autoresizingMask"/>
                             <subviews>
                                 <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="10 App IDs" textAlignment="natural" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Zna-7n-kBz">
-                                    <rect key="frame" x="146" y="0.0" width="83" height="21"/>
+                                    <rect key="frame" x="146.5" y="0.0" width="82" height="21"/>
                                     <fontDescription key="fontDescription" type="system" pointSize="17"/>
                                     <color key="textColor" white="0.5" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
                                     <nil key="highlightedColor"/>
@@ -934,7 +938,7 @@ World</string>
                     <collectionView key="view" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" preservesSuperviewLayoutMargins="YES" dataMode="prototypes" id="S36-hD-vu2">
                         <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
-                        <color key="backgroundColor" systemColor="systemBackgroundColor" cocoaTouchSystemColor="whiteColor"/>
+                        <color key="backgroundColor" systemColor="systemBackgroundColor"/>
                         <collectionViewFlowLayout key="collectionViewLayout" minimumLineSpacing="15" minimumInteritemSpacing="10" id="X20-b5-XEP">
                             <size key="itemSize" width="375" height="80"/>
                             <size key="headerReferenceSize" width="50" height="200"/>
@@ -1032,7 +1036,7 @@ World</string>
         </scene>
     </scenes>
     <inferredMetricsTieBreakers>
-        <segue reference="Qd6-ba-dIo"/>
+        <segue reference="de9-NH-aec"/>
         <segue reference="cnd-KK-o60"/>
     </inferredMetricsTieBreakers>
     <color key="tintColor" name="Primary"/>
@@ -1049,7 +1053,13 @@ World</string>
             <color red="1" green="1" blue="1" alpha="0.30000001192092896" colorSpace="custom" customColorSpace="sRGB"/>
         </namedColor>
         <namedColor name="Primary">
-            <color red="0.0039215686274509803" green="0.50196078431372548" blue="0.51764705882352946" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+            <color red="0.0040000001899898052" green="0.50199997425079346" blue="0.51800000667572021" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
         </namedColor>
+        <systemColor name="systemBackgroundColor">
+            <color white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+        </systemColor>
+        <systemColor name="tertiarySystemBackgroundColor">
+            <color white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+        </systemColor>
     </resources>
 </document>
diff --git a/AltStore/Browse/BrowseViewController.swift b/AltStore/Browse/BrowseViewController.swift
index 03dab2c1..5400ba06 100644
--- a/AltStore/Browse/BrowseViewController.swift
+++ b/AltStore/Browse/BrowseViewController.swift
@@ -28,6 +28,8 @@ class BrowseViewController: UICollectionViewController
     
     private var cachedItemSizes = [String: CGSize]()
     
+    @IBOutlet private var sourcesBarButtonItem: UIBarButtonItem!
+    
     override func viewDidLoad()
     {
         super.viewDidLoad()
@@ -35,9 +37,6 @@ class BrowseViewController: UICollectionViewController
         #if BETA
         self.dataSource.searchController.searchableKeyPaths = [#keyPath(InstalledApp.name)]
         self.navigationItem.searchController = self.dataSource.searchController
-        #else
-        // Hide Sources button for public version while in beta.
-        self.navigationItem.rightBarButtonItem = nil
         #endif
         
         self.prototypeCell.contentView.translatesAutoresizingMaskIntoConstraints = false
@@ -58,6 +57,8 @@ class BrowseViewController: UICollectionViewController
         
         self.fetchSource()
         self.updateDataSource()
+        
+        self.update()
     }
     
     @IBAction private func unwindFromSourcesViewController(_ segue: UIStoryboardSegue)
@@ -241,6 +242,12 @@ private extension BrowseViewController
             
             self.placeholderView.activityIndicatorView.stopAnimating()
         }
+        
+        #if !BETA
+        // Hide Sources button for public version if there's only 1 source.
+        let sources = Source.all(in: DatabaseManager.shared.viewContext)
+        self.navigationItem.rightBarButtonItem = (sources.count > 1) ? self.sourcesBarButtonItem : nil
+        #endif
     }
 }
 
diff --git a/AltStore/Sources/SourcesViewController.swift b/AltStore/Sources/SourcesViewController.swift
index 2497a240..57bd146d 100644
--- a/AltStore/Sources/SourcesViewController.swift
+++ b/AltStore/Sources/SourcesViewController.swift
@@ -12,6 +12,24 @@ import CoreData
 import AltStoreCore
 import Roxas
 
+struct SourceError: LocalizedError
+{
+    enum Code
+    {
+        case unsupported
+    }
+    
+    var code: Code
+    @Managed var source: Source
+    
+    var errorDescription: String? {
+        switch self.code
+        {
+        case .unsupported: return String(format: NSLocalizedString("The source “%@” is not supported by this version of AltStore.", comment: ""), self.$source.name)
+        }
+    }
+}
+
 class SourcesViewController: UICollectionViewController
 {
     var deepLinkSourceURL: URL? {
@@ -28,6 +46,11 @@ class SourcesViewController: UICollectionViewController
         super.viewDidLoad()
         
         self.collectionView.dataSource = self.dataSource
+        
+        #if !BETA
+        // Hide "Add Source" button for public version while in beta.
+        self.navigationItem.leftBarButtonItem = nil
+        #endif
     }
     
     override func viewWillAppear(_ animated: Bool)
@@ -143,6 +166,10 @@ private extension SourcesViewController
                 let sourceName = source.name
                 let managedObjectContext = source.managedObjectContext
                 
+                #if !BETA
+                guard Source.allowedIdentifiers.contains(source.identifier) else { throw SourceError(code: .unsupported, source: source) }
+                #endif
+                
                 DispatchQueue.main.async {
                     let alertController = UIAlertController(title: String(format: NSLocalizedString("Would you like to add the source “%@”?", comment: ""), sourceName),
                                                             message: NSLocalizedString("Sources control what apps appear in AltStore. Make sure to only add sources that you trust.", comment: ""), preferredStyle: .alert)
diff --git a/AltStoreCore/Model/Source.swift b/AltStoreCore/Model/Source.swift
index cc0f2e32..2138ac92 100644
--- a/AltStoreCore/Model/Source.swift
+++ b/AltStoreCore/Model/Source.swift
@@ -33,6 +33,10 @@ public extension Source
     #endif
     
     #endif
+    
+    static let exampleIdentifier = "io.altstore.example"
+    
+    static let allowedIdentifiers: Set<String> = [exampleIdentifier]
 }
 
 @objc(Source)