diff --git a/Signal.xcodeproj/project.pbxproj b/Signal.xcodeproj/project.pbxproj
index 6cd95074f..ee6f104b1 100644
--- a/Signal.xcodeproj/project.pbxproj
+++ b/Signal.xcodeproj/project.pbxproj
@@ -419,6 +419,7 @@
 		4C20B2B720CA0034001BAC90 /* ThreadViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4542DF51208B82E9007B4E76 /* ThreadViewModel.swift */; };
 		4C20B2B920CA10DE001BAC90 /* ConversationSearchViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C20B2B820CA10DE001BAC90 /* ConversationSearchViewController.swift */; };
 		4C4AEC4520EC343B0020E72B /* DismissableTextField.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4C4AEC4420EC343B0020E72B /* DismissableTextField.swift */; };
+		4C6F527C20FFE8400097DEEE /* SignalUBSan.supp in Resources */ = {isa = PBXBuildFile; fileRef = 4C6F527B20FFE8400097DEEE /* SignalUBSan.supp */; };
 		4CB5F26720F6E1E2004D1B42 /* MenuActionsViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CFF4C0920F55BBA005DA313 /* MenuActionsViewController.swift */; };
 		4CB5F26920F7D060004D1B42 /* MessageActions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CB5F26820F7D060004D1B42 /* MessageActions.swift */; };
 		4CC0B59C20EC5F2E00CF6EE0 /* ConversationConfigurationSyncOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CC0B59B20EC5F2E00CF6EE0 /* ConversationConfigurationSyncOperation.swift */; };
@@ -1084,6 +1085,7 @@
 		4C13C9F520E57BA30089A98B /* ColorPickerViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ColorPickerViewController.swift; sourceTree = "<group>"; };
 		4C20B2B820CA10DE001BAC90 /* ConversationSearchViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConversationSearchViewController.swift; sourceTree = "<group>"; };
 		4C4AEC4420EC343B0020E72B /* DismissableTextField.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DismissableTextField.swift; sourceTree = "<group>"; };
+		4C6F527B20FFE8400097DEEE /* SignalUBSan.supp */ = {isa = PBXFileReference; lastKnownFileType = text; path = SignalUBSan.supp; sourceTree = "<group>"; };
 		4CB5F26820F7D060004D1B42 /* MessageActions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MessageActions.swift; sourceTree = "<group>"; };
 		4CC0B59B20EC5F2E00CF6EE0 /* ConversationConfigurationSyncOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConversationConfigurationSyncOperation.swift; sourceTree = "<group>"; };
 		4CFF4C0920F55BBA005DA313 /* MenuActionsViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MenuActionsViewController.swift; sourceTree = "<group>"; };
@@ -2402,6 +2404,7 @@
 		D221A094169C9E5E00537ABF /* Supporting Files */ = {
 			isa = PBXGroup;
 			children = (
+				4C6F527B20FFE8400097DEEE /* SignalUBSan.supp */,
 				B6B6C3C419193F5B00C0B76B /* Translations */,
 				D221A099169C9E5E00537ABF /* main.m */,
 				D221A095169C9E5E00537ABF /* Signal-Info.plist */,
@@ -2754,6 +2757,7 @@
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				4C6F527C20FFE8400097DEEE /* SignalUBSan.supp in Resources */,
 				34CF078A203E6B78005C4D61 /* end_call_tone_cept.caf in Resources */,
 				AD83FF3F1A73426500B5C81A /* audio_pause_button_blue.png in Resources */,
 				34330A5A1E7875FB00DF2FB9 /* fontawesome-webfont.ttf in Resources */,
diff --git a/Signal.xcodeproj/xcshareddata/xcschemes/Signal.xcscheme b/Signal.xcodeproj/xcshareddata/xcschemes/Signal.xcscheme
index 7dd0b1819..78b9c56c1 100644
--- a/Signal.xcodeproj/xcshareddata/xcschemes/Signal.xcscheme
+++ b/Signal.xcodeproj/xcshareddata/xcschemes/Signal.xcscheme
@@ -28,7 +28,7 @@
             buildForAnalyzing = "YES">
             <BuildableReference
                BuildableIdentifier = "primary"
-               BlueprintIdentifier = "B57ACF2237BE640621E2E2CF12637CFE"
+               BlueprintIdentifier = "13CED0CFD8586E9C6BAC02E581D06068"
                BuildableName = "SignalServiceKit.framework"
                BlueprintName = "SignalServiceKit"
                ReferencedContainer = "container:Pods/Pods.xcodeproj">
@@ -83,6 +83,7 @@
       useCustomWorkingDirectory = "NO"
       ignoresPersistentStateOnLaunch = "NO"
       debugDocumentVersioning = "YES"
+      stopOnEveryUBSanitizerIssue = "YES"
       debugServiceExtension = "internal"
       allowLocationSimulation = "YES"
       showNonLocalizedStrings = "YES">
@@ -102,6 +103,11 @@
             value = "disable"
             isEnabled = "YES">
          </EnvironmentVariable>
+         <EnvironmentVariable
+            key = "UBSAN_OPTIONS"
+            value = "suppressions=SignalUBSan.supp"
+            isEnabled = "YES">
+         </EnvironmentVariable>
          <EnvironmentVariable
             key = "DYLD_PRINT_STATISTICS"
             value = "1"
diff --git a/Signal/SignalUBSan.supp b/Signal/SignalUBSan.supp
new file mode 100644
index 000000000..043c00979
--- /dev/null
+++ b/Signal/SignalUBSan.supp
@@ -0,0 +1,32 @@
+# See https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html#runtime-suppressions
+# for details.
+
+# protobuf lib
+shift-base:CodedInputStream.m
+# generated protos
+bool:WebSocketResources.pb.m
+bool:OWSSignalServiceProtos.pb.m
+bool:WhisperTextProtocol.pb.m
+bool:OWSWebRTCDataProtos.pb.m
+bool:OWSSignaliOSProtos.pb.m
+bool:OWSProvisioningProtos.pb.m
+bool:OWSFingerprintProtos.pb.m
+
+# YapDatabase
+bool:YapDatabaseAutoViewTransaction.m
+
+# SocketRocket
+bool:SRWebSocket.m
+
+# Curve25519 expected
+shift-base:curve25519-donna.c
+shift-base:ge_scalarmult_base.c
+shift-base:fe_mul.c
+shift-exponent:fe_sq.c
+shift-base:fe_sq.c
+shift-base:fe_sq2.c
+shift-exponent:fe_sq2.c
+shift-base:fe_tobytes.c
+shift-exponent:fe_tobytes.c
+shift-base:sc_reduce.c
+shift-exponent:sc_reduce.c
diff --git a/Signal/src/ViewControllers/AppSettings/OWSLinkedDevicesTableViewController.m b/Signal/src/ViewControllers/AppSettings/OWSLinkedDevicesTableViewController.m
index 9a4878119..f28f57bbf 100644
--- a/Signal/src/ViewControllers/AppSettings/OWSLinkedDevicesTableViewController.m
+++ b/Signal/src/ViewControllers/AppSettings/OWSLinkedDevicesTableViewController.m
@@ -75,9 +75,13 @@ int const OWSLinkedDevicesTableViewControllerSectionAddDevice = 1;
 {
     [super viewWillAppear:animated];
     [self refreshDevices];
-    // HACK to unselect rows when swiping back
-    // http://stackoverflow.com/questions/19379510/uitableviewcell-doesnt-get-deselected-when-swiping-back-quickly
-    [self.tableView deselectRowAtIndexPath:[self.tableView indexPathForSelectedRow] animated:animated];
+
+    NSIndexPath *_Nullable selectedPath = [self.tableView indexPathForSelectedRow];
+    if (selectedPath) {
+        // HACK to unselect rows when swiping back
+        // http://stackoverflow.com/questions/19379510/uitableviewcell-doesnt-get-deselected-when-swiping-back-quickly
+        [self.tableView deselectRowAtIndexPath:selectedPath animated:animated];
+    }
 }
 
 - (void)viewWillDisappear:(BOOL)animated
diff --git a/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageHeaderView.m b/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageHeaderView.m
index b687f8842..392ce64fe 100644
--- a/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageHeaderView.m
+++ b/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageHeaderView.m
@@ -43,6 +43,7 @@ const CGFloat OWSMessageHeaderViewDateHeaderVMargin = 23;
     OWSAssert(!self.titleLabel);
 
     self.layoutMargins = UIEdgeInsetsZero;
+    self.layoutConstraints = @[];
 
     // Intercept touches.
     // Date breaks and unread indicators are not interactive.
diff --git a/Signal/src/ViewControllers/ConversationView/Cells/OWSSystemMessageCell.m b/Signal/src/ViewControllers/ConversationView/Cells/OWSSystemMessageCell.m
index 2851ee105..7df6ba637 100644
--- a/Signal/src/ViewControllers/ConversationView/Cells/OWSSystemMessageCell.m
+++ b/Signal/src/ViewControllers/ConversationView/Cells/OWSSystemMessageCell.m
@@ -77,6 +77,7 @@ typedef void (^SystemMessageActionBlock)(void);
     self.layoutMargins = UIEdgeInsetsZero;
     self.contentView.layoutMargins = UIEdgeInsetsZero;
     self.contentView.backgroundColor = UIColor.whiteColor;
+    self.layoutConstraints = @[];
 
     self.headerView = [OWSMessageHeaderView new];
     self.headerViewHeightConstraint = [self.headerView autoSetDimension:ALDimensionHeight toSize:0];
diff --git a/Signal/src/ViewControllers/ThreadSettings/OWSConversationSettingsViewController.m b/Signal/src/ViewControllers/ThreadSettings/OWSConversationSettingsViewController.m
index 33983ab71..e90439722 100644
--- a/Signal/src/ViewControllers/ThreadSettings/OWSConversationSettingsViewController.m
+++ b/Signal/src/ViewControllers/ThreadSettings/OWSConversationSettingsViewController.m
@@ -847,9 +847,12 @@ const CGFloat kIconViewLength = 24;
 {
     [super viewWillAppear:animated];
 
-    // HACK to unselect rows when swiping back
-    // http://stackoverflow.com/questions/19379510/uitableviewcell-doesnt-get-deselected-when-swiping-back-quickly
-    [self.tableView deselectRowAtIndexPath:[self.tableView indexPathForSelectedRow] animated:animated];
+    NSIndexPath *_Nullable selectedPath = [self.tableView indexPathForSelectedRow];
+    if (selectedPath) {
+        // HACK to unselect rows when swiping back
+        // http://stackoverflow.com/questions/19379510/uitableviewcell-doesnt-get-deselected-when-swiping-back-quickly
+        [self.tableView deselectRowAtIndexPath:selectedPath animated:animated];
+    }
 
     [self updateTableContents];
 }