diff --git a/SignalServiceKit/src/Util/AppReadiness.m b/SignalServiceKit/src/Util/AppReadiness.m
index 95ba13e7c..44a68cfe9 100755
--- a/SignalServiceKit/src/Util/AppReadiness.m
+++ b/SignalServiceKit/src/Util/AppReadiness.m
@@ -3,6 +3,7 @@
 //
 
 #import "AppReadiness.h"
+#import "Threading.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -48,9 +49,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (void)runNowOrWhenAppIsReady:(AppReadyBlock)block
 {
-    OWSAssertIsOnMainThread();
-
-    [self.sharedManager runNowOrWhenAppIsReady:block];
+    DispatchMainThreadSafe(^{
+        [self.sharedManager runNowOrWhenAppIsReady:block];
+    });
 }
 
 - (void)runNowOrWhenAppIsReady:(AppReadyBlock)block
diff --git a/SignalServiceKit/src/Util/Threading.h b/SignalServiceKit/src/Util/Threading.h
index 4aac9cec7..dca1d19a7 100644
--- a/SignalServiceKit/src/Util/Threading.h
+++ b/SignalServiceKit/src/Util/Threading.h
@@ -4,16 +4,14 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-typedef void (^SimpleBlock)(void);
-
 // The block is executed immediately if called from the
 // main thread; otherwise it is dispatched async to the
 // main thread.
-void DispatchMainThreadSafe(SimpleBlock block);
+void DispatchMainThreadSafe(dispatch_block_t block);
 
 // The block is executed immediately if called from the
 // main thread; otherwise it is dispatched sync to the
 // main thread.
-void DispatchSyncMainThreadSafe(SimpleBlock block);
+void DispatchSyncMainThreadSafe(dispatch_block_t block);
 
 NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/src/Util/Threading.m b/SignalServiceKit/src/Util/Threading.m
index 72505e339..be0f00501 100644
--- a/SignalServiceKit/src/Util/Threading.m
+++ b/SignalServiceKit/src/Util/Threading.m
@@ -6,7 +6,7 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-void DispatchMainThreadSafe(SimpleBlock block)
+void DispatchMainThreadSafe(dispatch_block_t block)
 {
     OWSCAssert(block);
 
@@ -19,7 +19,7 @@ void DispatchMainThreadSafe(SimpleBlock block)
     }
 }
 
-void DispatchSyncMainThreadSafe(SimpleBlock block)
+void DispatchSyncMainThreadSafe(dispatch_block_t block)
 {
     OWSCAssert(block);