diff --git a/src/auth/auth-worker-client.c b/src/auth/auth-worker-client.c
index 4d07018a3d..172b3816f0 100644
--- a/src/auth/auth-worker-client.c
+++ b/src/auth/auth-worker-client.c
@@ -117,7 +117,7 @@ static void auth_worker_send_reply(struct auth_worker_client *client,
 	if (worker_restart_request)
 		o_stream_nsend_str(client->output, "RESTART\n");
 	o_stream_nsend(client->output, str_data(str), str_len(str));
-	if (o_stream_nfinish(client->output) < 0 && request != NULL &&
+	if (o_stream_flush(client->output) < 0 && request != NULL &&
 	    cmd_duration > AUTH_WORKER_WARN_DISCONNECTED_LONG_CMD_SECS) {
 		p = i_strchr_to_next(str_c(str), '\t');
 		p = p == NULL ? "BUG" : t_strcut(p, '\t');
diff --git a/src/lib-auth/auth-master.c b/src/lib-auth/auth-master.c
index b4f3a30e42..216e1c7f58 100644
--- a/src/lib-auth/auth-master.c
+++ b/src/lib-auth/auth-master.c
@@ -406,7 +406,7 @@ static int auth_master_run_cmd_pre(struct auth_master_connection *conn,
 	o_stream_nsend_str(conn->output, cmd);
 	o_stream_uncork(conn->output);
 
-	if (o_stream_nfinish(conn->output) < 0) {
+	if (o_stream_flush(conn->output) < 0) {
 		i_error("write(auth socket) failed: %s",
 			o_stream_get_error(conn->output));
 		auth_master_unset_io(conn);
diff --git a/src/lib-fs/fs-api.h b/src/lib-fs/fs-api.h
index eaadcc8a8a..6811961802 100644
--- a/src/lib-fs/fs-api.h
+++ b/src/lib-fs/fs-api.h
@@ -274,7 +274,7 @@ int fs_write(struct fs_file *file, const void *data, size_t size);
    fs_write_stream_finish/abort. The returned ostream is already corked and
    it doesn't need to be uncorked. */
 struct ostream *fs_write_stream(struct fs_file *file);
-/* Finish writing via stream, calling also o_stream_nfinish() on the stream and
+/* Finish writing via stream, calling also o_stream_flush() on the stream and
    handling any pending errors. The file will be created/replaced/appended only
    after this call, same as with fs_write(). Anything written to the stream
    won't be visible earlier. Returns 1 if ok, 0 if async write isn't finished
diff --git a/src/lib-storage/index/dbox-common/dbox-file-fix.c b/src/lib-storage/index/dbox-common/dbox-file-fix.c
index f2684fcad5..6ed7904d28 100644
--- a/src/lib-storage/index/dbox-common/dbox-file-fix.c
+++ b/src/lib-storage/index/dbox-common/dbox-file-fix.c
@@ -243,7 +243,7 @@ stream_copy(struct dbox_file *file, struct ostream *output,
 			"read(%s) failed: %s", file->cur_path,
 			i_stream_get_error(input));
 		ret = -1;
-	} else if (o_stream_nfinish(output) < 0) {
+	} else if (o_stream_flush(output) < 0) {
 		mail_storage_set_critical(&file->storage->storage,
 			"write(%s) failed: %s", out_path,
 			o_stream_get_error(output));
@@ -436,7 +436,7 @@ dbox_file_fix_write_stream(struct dbox_file *file, uoff_t start_offset,
 		if (output->stream_errno != 0)
 			break;
 	}
-	if (o_stream_nfinish(output) < 0) {
+	if (o_stream_flush(output) < 0) {
 		mail_storage_set_critical(&file->storage->storage,
 			"write(%s) failed: %s", temp_path, o_stream_get_error(output));
 		ret = -1;
diff --git a/src/lib-storage/index/dbox-common/dbox-file.c b/src/lib-storage/index/dbox-common/dbox-file.c
index fa14f48432..0b3aed167e 100644
--- a/src/lib-storage/index/dbox-common/dbox-file.c
+++ b/src/lib-storage/index/dbox-common/dbox-file.c
@@ -551,7 +551,7 @@ int dbox_file_append_flush(struct dbox_file_append_context *ctx)
 	    ctx->last_checkpoint_offset == ctx->output->offset)
 		return 0;
 
-	if (o_stream_nfinish(ctx->output) < 0) {
+	if (o_stream_flush(ctx->output) < 0) {
 		dbox_file_set_syscall_error(ctx->file, "write()");
 		return -1;
 	}
diff --git a/src/lib-storage/index/dbox-common/dbox-save.c b/src/lib-storage/index/dbox-common/dbox-save.c
index 619a7aba74..91424c8e2b 100644
--- a/src/lib-storage/index/dbox-common/dbox-save.c
+++ b/src/lib-storage/index/dbox-common/dbox-save.c
@@ -104,7 +104,7 @@ void dbox_save_end(struct dbox_save_context *ctx)
 		ret = o_stream_finish(mdata->output);
 	} else {
 		/* no plugins - flush the output so far */
-		ret = o_stream_nfinish(mdata->output);
+		ret = o_stream_flush(mdata->output);
 	}
 	if (ret < 0) {
 		mail_storage_set_critical(ctx->ctx.transaction->box->storage,
diff --git a/src/lib-storage/index/dbox-multi/mdbox-purge.c b/src/lib-storage/index/dbox-multi/mdbox-purge.c
index 1dd4244b76..704d855f5a 100644
--- a/src/lib-storage/index/dbox-multi/mdbox-purge.c
+++ b/src/lib-storage/index/dbox-multi/mdbox-purge.c
@@ -207,7 +207,7 @@ mdbox_purge_save_msg(struct mdbox_purge_context *ctx, struct dbox_file *file,
 
 	input = i_stream_create_limit(file->input, msg_size);
 	o_stream_nsend_istream(output, input);
-	if (o_stream_nfinish(output) < 0) {
+	if (o_stream_flush(output) < 0) {
 		mail_storage_set_critical(&file->storage->storage,
 					  "write(%s) failed: %s",
 					  out_file_append->file->cur_path,
diff --git a/src/lib-storage/index/mbox/mbox-save.c b/src/lib-storage/index/mbox/mbox-save.c
index ef1759dbbb..3a13150c48 100644
--- a/src/lib-storage/index/mbox/mbox-save.c
+++ b/src/lib-storage/index/mbox/mbox-save.c
@@ -659,7 +659,7 @@ int mbox_save_finish(struct mail_save_context *_ctx)
 
 	if (ctx->output != NULL) {
 		/* make sure everything is written */
-		if (o_stream_nfinish(ctx->output) < 0)
+		if (o_stream_flush(ctx->output) < 0)
 			write_error(ctx);
 	}
 
@@ -681,7 +681,7 @@ int mbox_save_finish(struct mail_save_context *_ctx)
 
 	if (ctx->failed && ctx->mail_offset != (uoff_t)-1) {
 		/* saving this mail failed - truncate back to beginning of it */
-		(void)o_stream_nfinish(ctx->output);
+		(void)o_stream_flush(ctx->output);
 		if (ftruncate(ctx->mbox->mbox_fd, (off_t)ctx->mail_offset) < 0)
 			mbox_set_syscall_error(ctx->mbox, "ftruncate()");
 		(void)o_stream_seek(ctx->output, ctx->mail_offset);
@@ -775,7 +775,7 @@ int mbox_transaction_save_commit_pre(struct mail_save_context *_ctx)
 
 	if (ctx->output != NULL) {
 		/* flush the final LF */
-		if (o_stream_nfinish(ctx->output) < 0)
+		if (o_stream_flush(ctx->output) < 0)
 			write_error(ctx);
 	}
 	if (mbox->mbox_fd != -1 && !mbox->mbox_writeonly &&
diff --git a/src/lib/iostream-rawlog.c b/src/lib/iostream-rawlog.c
index e4e800c11a..ea41a35e20 100644
--- a/src/lib/iostream-rawlog.c
+++ b/src/lib/iostream-rawlog.c
@@ -125,7 +125,7 @@ void iostream_rawlog_write(struct rawlog_iostream *rstream,
 		iostream_rawlog_write_unbuffered(rstream, data, size);
 	o_stream_uncork(rstream->rawlog_output);
 
-	if (o_stream_nfinish(rstream->rawlog_output) < 0) {
+	if (o_stream_flush(rstream->rawlog_output) < 0) {
 		i_error("write(%s) failed: %s",
 			o_stream_get_name(rstream->rawlog_output),
 			o_stream_get_error(rstream->rawlog_output));
diff --git a/src/lmtp/commands.c b/src/lmtp/commands.c
index 4ade60083e..45915293a7 100644
--- a/src/lmtp/commands.c
+++ b/src/lmtp/commands.c
@@ -1256,7 +1256,7 @@ static int client_input_add_file(struct client *client,
 	o_stream_nsend(state->mail_data_output,
 		       state->mail_data->data, state->mail_data->used);
 	o_stream_nsend(client->state.mail_data_output, data, size);
-	if (o_stream_nfinish(client->state.mail_data_output) < 0) {
+	if (o_stream_flush(client->state.mail_data_output) < 0) {
 		i_error("write(%s) failed: %s", str_c(path),
 			o_stream_get_error(client->state.mail_data_output));
 		return -1;