diff --git a/Podfile.lock b/Podfile.lock
index d9a1338fb4..04daa08c19 100644
--- a/Podfile.lock
+++ b/Podfile.lock
@@ -132,7 +132,7 @@ CHECKOUT OPTIONS:
     :commit: cbf2f47d59dd54d6d720fe787f835bd767443bb6
     :git: https://github.com/WhisperSystems/SignalProtocolKit.git
   SignalServiceKit:
-    :commit: 4f9e053248dd87f59e198be5d00be5b9bd48bfa9
+    :commit: 45b8dc9c96fe3aeb6e0c46eff7912670d2fc41a9
     :git: https://github.com/WhisperSystems/SignalServiceKit.git
   SocketRocket:
     :commit: 877ac7438be3ad0b45ef5ca3969574e4b97112bf
diff --git a/Signal/Signal-Prefix.pch b/Signal/Signal-Prefix.pch
index f5ce9f9e98..fb20452f68 100644
--- a/Signal/Signal-Prefix.pch
+++ b/Signal/Signal-Prefix.pch
@@ -19,7 +19,7 @@
     #import <SignalServiceKit/Constraints.h>
     #import <SignalServiceKit/OWSAnalytics.h>
     #import <SignalServiceKit/OWSDispatch.h>
-    #import "iOSVersions.h"
+    #import <SignalServiceKit/iOSVersions.h>
 
     #define SignalAlertView(title,msg) [[[UIAlertView alloc] initWithTitle:title message:msg delegate:nil cancelButtonTitle:NSLocalizedString(@"OK", @"") otherButtonTitles:nil, nil] show]    
 #endif
diff --git a/Signal/src/AppDelegate.m b/Signal/src/AppDelegate.m
index a991ef06dd..88d303f19a 100644
--- a/Signal/src/AppDelegate.m
+++ b/Signal/src/AppDelegate.m
@@ -191,7 +191,7 @@ static NSString *const kURLHostVerifyPrefix             = @"verify";
     [Environment setCurrent:[Release releaseEnvironment]];
 
     // Encryption/Descryption mutates session state and must be synchronized on a serial queue.
-    [SessionCipher setSessionCipherDispatchQueue:[OWSDispatch sessionCipher]];
+    [SessionCipher setSessionCipherDispatchQueue:[OWSDispatch sessionStoreQueue]];
 
     TextSecureKitEnv *sharedEnv =
         [[TextSecureKitEnv alloc] initWithCallMessageHandler:[Environment getCurrent].callMessageHandler
diff --git a/Signal/src/ViewControllers/DebugUITableViewController.m b/Signal/src/ViewControllers/DebugUITableViewController.m
index 2af90b643f..300080ed3b 100644
--- a/Signal/src/ViewControllers/DebugUITableViewController.m
+++ b/Signal/src/ViewControllers/DebugUITableViewController.m
@@ -67,12 +67,29 @@ NS_ASSUME_NONNULL_BEGIN
                                                       }],
                                   ]]];
 
-    [contents addSection:[OWSTableSection sectionWithTitle:@"Print to Debug Log"
-                                                     items:@[ [OWSTableItem itemWithTitle:@"Print all sessions"
-                                                                              actionBlock:^{
-                                                                                  [[TSStorageManager sharedManager]
-                                                                                      printAllSessions];
-                                                                              }] ]]];
+    [contents
+        addSection:[OWSTableSection
+                       sectionWithTitle:@"Session State"
+                                  items:@[
+                                      [OWSTableItem itemWithTitle:@"Print all sessions"
+                                                      actionBlock:^{
+                                                          dispatch_async([OWSDispatch sessionStoreQueue], ^{
+                                                              [[TSStorageManager sharedManager] printAllSessions];
+                                                          });
+                                                      }],
+                                      [OWSTableItem itemWithTitle:@"Delete session (Contact Thread Only)"
+                                                      actionBlock:^{
+                                                          if (![thread isKindOfClass:[TSContactThread class]]) {
+                                                              DDLogError(@"Trying to delete session for group thread.");
+                                                              OWSAssert(NO);
+                                                          }
+                                                          dispatch_async([OWSDispatch sessionStoreQueue], ^{
+                                                              [[TSStorageManager sharedManager]
+                                                                  deleteAllSessionsForContact:thread.contactIdentifier];
+                                                          });
+                                                      }],
+
+                                  ]]];
 
     DebugUITableViewController *viewController = [DebugUITableViewController new];
     viewController.contents = contents;
diff --git a/Signal/src/environment/iOSVersions.h b/Signal/src/environment/iOSVersions.h
deleted file mode 100644
index d1f60d207d..0000000000
--- a/Signal/src/environment/iOSVersions.h
+++ /dev/null
@@ -1,14 +0,0 @@
-//
-//  iOSVersions.h
-//  Signal
-//
-//  Created by Frederic Jacobs on 03/08/14.
-//  Copyright (c) 2014 Open Whisper Systems. All rights reserved.
-//
-
-#import <Foundation/Foundation.h>
-#include <Availability.h>
-
-#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(major, minor) \
-    ([[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){.majorVersion = major, .minorVersion = minor, .patchVersion = 0}])
-
diff --git a/Signal/src/util/UIFont+OWS.m b/Signal/src/util/UIFont+OWS.m
index 8f5aa895e4..7757294aee 100644
--- a/Signal/src/util/UIFont+OWS.m
+++ b/Signal/src/util/UIFont+OWS.m
@@ -3,7 +3,6 @@
 //
 
 #import "UIFont+OWS.h"
-#import "iOSVersions.h"
 
 @implementation UIFont (OWS)