diff --git a/fs_mgr/libsnapshot/cow_reader.cpp b/fs_mgr/libsnapshot/cow_reader.cpp
index b3198a092..af49c7d3e 100644
--- a/fs_mgr/libsnapshot/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/cow_reader.cpp
@@ -381,10 +381,10 @@ bool CowReader::PrepMergeOps() {
     std::set<int, std::greater<int>> other_ops;
     auto seq_ops_set = std::unordered_set<uint32_t>();
     auto block_map = std::make_shared<std::unordered_map<uint32_t, int>>();
-    int num_seqs = 0;
+    size_t num_seqs = 0;
     size_t read;
 
-    for (int i = 0; i < ops_->size(); i++) {
+    for (size_t i = 0; i < ops_->size(); i++) {
         auto& current_op = ops_->data()[i];
 
         if (current_op.type == kCowSequenceOp) {
@@ -396,7 +396,7 @@ bool CowReader::PrepMergeOps() {
                 PLOG(ERROR) << "Failed to read sequence op!";
                 return false;
             }
-            for (int j = num_seqs; j < num_seqs + seq_len; j++) {
+            for (size_t j = num_seqs; j < num_seqs + seq_len; j++) {
                 seq_ops_set.insert(merge_op_blocks->data()[j]);
             }
             num_seqs += seq_len;
@@ -413,10 +413,11 @@ bool CowReader::PrepMergeOps() {
         }
         block_map->insert({current_op.new_block, i});
     }
-    if (merge_op_blocks->size() > header_.num_merge_ops)
+    if (merge_op_blocks->size() > header_.num_merge_ops) {
         num_ordered_ops_to_merge_ = merge_op_blocks->size() - header_.num_merge_ops;
-    else
+    } else {
         num_ordered_ops_to_merge_ = 0;
+    }
     merge_op_blocks->reserve(merge_op_blocks->size() + other_ops.size());
     for (auto block : other_ops) {
         merge_op_blocks->emplace_back(block);
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
index 05f70662c..6c3059c81 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
@@ -126,6 +126,10 @@ class CowReader : public ICowReader {
 
     bool GetRawBytes(uint64_t offset, void* buffer, size_t len, size_t* read);
 
+    // Returns the total number of data ops that should be merged. This is the
+    // count of the merge sequence before removing already-merged operations.
+    // It may be different than the actual data op count, for example, if there
+    // are duplicate ops in the stream.
     uint64_t get_num_total_data_ops() { return num_total_data_ops_; }
 
     uint64_t get_num_ordered_ops_to_merge() { return num_ordered_ops_to_merge_; }
diff --git a/fs_mgr/libsnapshot/snapshot.cpp b/fs_mgr/libsnapshot/snapshot.cpp
index 0e36da151..bed5f563d 100644
--- a/fs_mgr/libsnapshot/snapshot.cpp
+++ b/fs_mgr/libsnapshot/snapshot.cpp
@@ -1193,11 +1193,7 @@ MergeFailureCode SnapshotManager::CheckMergeConsistency(LockedFile* lock, const
             return MergeFailureCode::ParseCowConsistencyCheck;
         }
 
-        for (auto iter = reader.GetOpIter(); !iter->Done(); iter->Next()) {
-            if (!IsMetadataOp(iter->Get())) {
-                num_ops++;
-            }
-        }
+        num_ops = reader.get_num_total_data_ops();
     }
 
     // Second pass, try as hard as we can to get the actual number of blocks
diff --git a/fs_mgr/libsnapshot/snapshot_test.cpp b/fs_mgr/libsnapshot/snapshot_test.cpp
index 60186434a..b2203fe63 100644
--- a/fs_mgr/libsnapshot/snapshot_test.cpp
+++ b/fs_mgr/libsnapshot/snapshot_test.cpp
@@ -1184,6 +1184,53 @@ TEST_F(SnapshotUpdateTest, FullUpdateFlow) {
     }
 }
 
+TEST_F(SnapshotUpdateTest, DuplicateOps) {
+    if (!IsCompressionEnabled()) {
+        GTEST_SKIP() << "Compression-only test";
+    }
+
+    // OTA client blindly unmaps all partitions that are possibly mapped.
+    for (const auto& name : {"sys_b", "vnd_b", "prd_b"}) {
+        ASSERT_TRUE(sm->UnmapUpdateSnapshot(name));
+    }
+
+    // Execute the update.
+    ASSERT_TRUE(sm->BeginUpdate());
+    ASSERT_TRUE(sm->CreateUpdateSnapshots(manifest_));
+
+    // Write some data to target partitions.
+    for (const auto& name : {"sys_b", "vnd_b", "prd_b"}) {
+        ASSERT_TRUE(WriteSnapshotAndHash(name));
+    }
+
+    std::vector<PartitionUpdate*> partitions = {sys_, vnd_, prd_};
+    for (auto* partition : partitions) {
+        AddOperation(partition);
+
+        std::unique_ptr<ISnapshotWriter> writer;
+        auto res = MapUpdateSnapshot(partition->partition_name() + "_b", &writer);
+        ASSERT_TRUE(res);
+        ASSERT_TRUE(writer->AddZeroBlocks(0, 1));
+        ASSERT_TRUE(writer->AddZeroBlocks(0, 1));
+        ASSERT_TRUE(writer->Finalize());
+    }
+
+    ASSERT_TRUE(sm->FinishedSnapshotWrites(false));
+
+    // Simulate shutting down the device.
+    ASSERT_TRUE(UnmapAll());
+
+    // After reboot, init does first stage mount.
+    auto init = NewManagerForFirstStageMount("_b");
+    ASSERT_NE(init, nullptr);
+    ASSERT_TRUE(init->NeedSnapshotsInFirstStageMount());
+    ASSERT_TRUE(init->CreateLogicalAndSnapshotPartitions("super", snapshot_timeout_));
+
+    // Initiate the merge and wait for it to be completed.
+    ASSERT_TRUE(init->InitiateMerge());
+    ASSERT_EQ(UpdateState::MergeCompleted, init->ProcessUpdateState());
+}
+
 // Test that shrinking and growing partitions at the same time is handled
 // correctly in VABC.
 TEST_F(SnapshotUpdateTest, SpaceSwapUpdate) {
diff --git a/fs_mgr/libsnapshot/snapuserd.cpp b/fs_mgr/libsnapshot/snapuserd.cpp
index e578a7676..a09b1111c 100644
--- a/fs_mgr/libsnapshot/snapuserd.cpp
+++ b/fs_mgr/libsnapshot/snapuserd.cpp
@@ -64,7 +64,7 @@ bool Snapuserd::CommitMerge(int num_merge_ops) {
 
     int ret = msync(mapped_addr_, BLOCK_SZ, MS_SYNC);
     if (ret < 0) {
-        PLOG(ERROR) << "msync header failed: " << ret;
+        SNAP_PLOG(ERROR) << "msync header failed: " << ret;
         return false;
     }