diff --git a/Sources/Amplitude/Amplitude.m b/Sources/Amplitude/Amplitude.m
index 12ecda99..90f84a2d 100644
--- a/Sources/Amplitude/Amplitude.m
+++ b/Sources/Amplitude/Amplitude.m
@@ -680,6 +680,7 @@ - (void)logEvent:(NSString *)eventType withEventProperties:(NSDictionary *)event
     userProperties = [userProperties copy];
     groups = [groups copy];
     groupProperties = [groupProperties copy];
+    extra = [extra copy];
     BOOL inForeground = _inForeground;
 
     [self runOnBackgroundQueue:^{