diff --git a/fdbclient/BackupContainerAzureBlobStore.actor.cpp b/fdbclient/BackupContainerAzureBlobStore.actor.cpp
index b8e9a9214b..55b70e9ddc 100644
--- a/fdbclient/BackupContainerAzureBlobStore.actor.cpp
+++ b/fdbclient/BackupContainerAzureBlobStore.actor.cpp
@@ -130,7 +130,8 @@ public:
 		int64_t m_offset;
 
 	public:
-		BackupFile(const std::string& fileName, Reference<IAsyncFile> file) : IBackupFile(fileName), m_file(file) {}
+		BackupFile(const std::string& fileName, Reference<IAsyncFile> file)
+		  : IBackupFile(fileName), m_file(file), m_offset(0) {}
 		Future<Void> append(const void* data, int len) override {
 			Future<Void> r = m_file->write(data, len, m_offset);
 			m_offset += len;
diff --git a/fdbclient/BackupContainerLocalDirectory.actor.cpp b/fdbclient/BackupContainerLocalDirectory.actor.cpp
index 388271d743..9fb47fa036 100644
--- a/fdbclient/BackupContainerLocalDirectory.actor.cpp
+++ b/fdbclient/BackupContainerLocalDirectory.actor.cpp
@@ -31,7 +31,7 @@ namespace {
 class BackupFile : public IBackupFile, ReferenceCounted<BackupFile> {
 public:
 	BackupFile(std::string fileName, Reference<IAsyncFile> file, std::string finalFullPath)
-	  : IBackupFile(fileName), m_file(file), m_finalFullPath(finalFullPath) {}
+	  : IBackupFile(fileName), m_file(file), m_finalFullPath(finalFullPath), m_offset(0) {}
 
 	Future<Void> append(const void* data, int len) {
 		Future<Void> r = m_file->write(data, len, m_offset);
diff --git a/fdbclient/BackupContainerS3BlobStore.actor.cpp b/fdbclient/BackupContainerS3BlobStore.actor.cpp
index 085e88caf6..c233b16778 100644
--- a/fdbclient/BackupContainerS3BlobStore.actor.cpp
+++ b/fdbclient/BackupContainerS3BlobStore.actor.cpp
@@ -45,7 +45,8 @@ public:
 
 	class BackupFile : public IBackupFile, ReferenceCounted<BackupFile> {
 	public:
-		BackupFile(std::string fileName, Reference<IAsyncFile> file) : IBackupFile(fileName), m_file(file) {}
+		BackupFile(std::string fileName, Reference<IAsyncFile> file)
+		  : IBackupFile(fileName), m_file(file), m_offset(0) {}
 
 		Future<Void> append(const void* data, int len) {
 			Future<Void> r = m_file->write(data, len, m_offset);