diff --git a/Objective-C/CBLDatabase.mm b/Objective-C/CBLDatabase.mm
index 1f29d6ac3..5c200f2e4 100644
--- a/Objective-C/CBLDatabase.mm
+++ b/Objective-C/CBLDatabase.mm
@@ -1122,13 +1122,12 @@ - (void) postDatabaseChanged {
         const uint32_t kMaxChanges = 100u;
         C4DatabaseChange changes[kMaxChanges];
         bool external = false;
-        uint32_t nChanges = 0u;
+        C4CollectionObservation obs = {};
         NSMutableArray* docIDs = [NSMutableArray new];
         do {
             // Read changes in batches of kMaxChanges:
-            bool newExternal;
-            nChanges = c4dbobs_getChanges(_dbObs, changes, kMaxChanges, &newExternal);
-            if (nChanges == 0 || external != newExternal || docIDs.count > 1000) {
+            obs = c4dbobs_getChanges(_dbObs, changes, kMaxChanges);
+            if (obs.numChanges == 0 || external != obs.external || docIDs.count > 1000) {
                 if(docIDs.count > 0) {
 // TODO: Remove https://issues.couchbase.com/browse/CBL-3206
 #pragma clang diagnostic push
@@ -1137,19 +1136,19 @@ - (void) postDatabaseChanged {
                     [_dbChangeNotifier postChange:
                         [[CBLDatabaseChange alloc] initWithDatabase: self
                                                         documentIDs: docIDs
-                                                         isExternal: external] ];
+                                                         isExternal: external]];
 #pragma clang diagnostic pop
                     docIDs = [NSMutableArray new];
                 }
             }
             
-            external = newExternal;
-            for(uint32_t i = 0; i < nChanges; i++) {
+            external = obs.external;
+            for(uint32_t i = 0; i < obs.numChanges; i++) {
                 NSString *docID =slice2string(changes[i].docID);
                 [docIDs addObject: docID];
             }
-            c4dbobs_releaseChanges(changes, nChanges);
-        } while(nChanges > 0);
+            c4dbobs_releaseChanges(changes, obs.numChanges);
+        } while(obs.numChanges > 0);
     }
 }
 
diff --git a/Objective-C/Internal/CBLDocumentChangeNotifier.mm b/Objective-C/Internal/CBLDocumentChangeNotifier.mm
index f7542f61c..11841120f 100644
--- a/Objective-C/Internal/CBLDocumentChangeNotifier.mm
+++ b/Objective-C/Internal/CBLDocumentChangeNotifier.mm
@@ -41,8 +41,8 @@ - (instancetype) initWithDatabase: (CBLDatabase*)db
     return self;
 }
 
-static void docObserverCallback(C4DocumentObserver* obs, C4Slice docID, C4SequenceNumber seq,
-                                void *context)
+static void docObserverCallback(C4DocumentObserver* obs, C4Collection* collection,
+                                C4Slice docID, C4SequenceNumber seq, void *context)
 {
     [(__bridge CBLDocumentChangeNotifier*)context postChange];
 }