diff --git a/AltStore/Base.lproj/Main.storyboard b/AltStore/Base.lproj/Main.storyboard
index b7041ee1..85234248 100644
--- a/AltStore/Base.lproj/Main.storyboard
+++ b/AltStore/Base.lproj/Main.storyboard
@@ -1002,10 +1002,10 @@ World</string>
                                 </label>
                             </subviews>
                             <constraints>
-                                <constraint firstItem="TZv-TM-uJj" firstAttribute="top" secondItem="8N7-JY-mcA" secondAttribute="top" constant="14" id="2zE-UV-24S"/>
-                                <constraint firstAttribute="bottom" secondItem="TZv-TM-uJj" secondAttribute="bottom" constant="15" id="Aml-PC-dko"/>
-                                <constraint firstAttribute="trailingMargin" secondItem="TZv-TM-uJj" secondAttribute="trailing" id="V0U-al-5eb"/>
-                                <constraint firstAttribute="leadingMargin" secondItem="TZv-TM-uJj" secondAttribute="leading" id="aS5-6Y-rMd"/>
+                                <constraint firstItem="TZv-TM-uJj" firstAttribute="top" secondItem="8N7-JY-mcA" secondAttribute="top" priority="999" constant="14" id="2zE-UV-24S"/>
+                                <constraint firstAttribute="bottom" secondItem="TZv-TM-uJj" secondAttribute="bottom" priority="999" constant="15" id="Aml-PC-dko"/>
+                                <constraint firstAttribute="trailingMargin" secondItem="TZv-TM-uJj" secondAttribute="trailing" priority="999" id="V0U-al-5eb"/>
+                                <constraint firstAttribute="leadingMargin" secondItem="TZv-TM-uJj" secondAttribute="leading" priority="999" id="aS5-6Y-rMd"/>
                             </constraints>
                             <connections>
                                 <outlet property="bottomLayoutConstraint" destination="Aml-PC-dko" id="I1s-ae-C8A"/>
diff --git a/AltStore/Sources/SourcesViewController.swift b/AltStore/Sources/SourcesViewController.swift
index 96ff8798..8c86ecc7 100644
--- a/AltStore/Sources/SourcesViewController.swift
+++ b/AltStore/Sources/SourcesViewController.swift
@@ -500,11 +500,12 @@ extension SourcesViewController: UICollectionViewDelegateFlowLayout
         headerView.layoutMargins.left = self.view.layoutMargins.left
         headerView.layoutMargins.right = self.view.layoutMargins.right
         
-        let almostRequiredPriority = UILayoutPriority(UILayoutPriority.required.rawValue - 1) // Can't be required or else we can't satisfy constraints when hidden (size = 0).
-        headerView.leadingLayoutConstraint?.priority = almostRequiredPriority
-        headerView.trailingLayoutConstraint?.priority = almostRequiredPriority
-        headerView.topLayoutConstraint?.priority = almostRequiredPriority
-        headerView.bottomLayoutConstraint?.priority = almostRequiredPriority
+        /* Changing NSLayoutConstraint priorities from required to optional (and vice versa) isn’t supported, and crashes on iOS 12. */
+        // let almostRequiredPriority = UILayoutPriority(UILayoutPriority.required.rawValue - 1) // Can't be required or else we can't satisfy constraints when hidden (size = 0).
+        // headerView.leadingLayoutConstraint?.priority = almostRequiredPriority
+        // headerView.trailingLayoutConstraint?.priority = almostRequiredPriority
+        // headerView.topLayoutConstraint?.priority = almostRequiredPriority
+        // headerView.bottomLayoutConstraint?.priority = almostRequiredPriority
         
         switch kind
         {