diff --git a/reftable/block.c b/reftable/block.c
index 697b8b41531..f5b432566a6 100644
--- a/reftable/block.c
+++ b/reftable/block.c
@@ -40,7 +40,9 @@ int footer_size(int version)
 static int block_writer_register_restart(struct block_writer *w, int n,
 					 int is_restart, struct reftable_buf *key)
 {
-	int rlen = w->restart_len;
+	int rlen, err;
+
+	rlen = w->restart_len;
 	if (rlen >= MAX_RESTARTS) {
 		is_restart = 0;
 	}
@@ -60,7 +62,10 @@ static int block_writer_register_restart(struct block_writer *w, int n,
 	w->next += n;
 
 	reftable_buf_reset(&w->last_key);
-	reftable_buf_add(&w->last_key, key->buf, key->len);
+	err = reftable_buf_add(&w->last_key, key->buf, key->len);
+	if (err < 0)
+		return err;
+
 	w->entries++;
 	return 0;
 }
diff --git a/reftable/iter.c b/reftable/iter.c
index 6c193fd31a9..86e801ca9fb 100644
--- a/reftable/iter.c
+++ b/reftable/iter.c
@@ -197,7 +197,10 @@ int indexed_table_ref_iter_new(struct indexed_table_ref_iter **dest,
 
 	*itr = empty;
 	itr->r = r;
-	reftable_buf_add(&itr->oid, oid, oid_len);
+
+	err = reftable_buf_add(&itr->oid, oid, oid_len);
+	if (err < 0)
+		goto out;
 
 	itr->offsets = offsets;
 	itr->offset_len = offset_len;
diff --git a/reftable/reader.c b/reftable/reader.c
index ab89efd9c55..90dc950b577 100644
--- a/reftable/reader.c
+++ b/reftable/reader.c
@@ -769,7 +769,10 @@ static int reftable_reader_refs_for_unindexed(struct reftable_reader *r,
 	}
 	*filter = empty;
 
-	reftable_buf_add(&filter->oid, oid, oid_len);
+	err = reftable_buf_add(&filter->oid, oid, oid_len);
+	if (err < 0)
+		goto out;
+
 	iterator_from_table_iter(&filter->it, ti);
 
 	iterator_from_filtering_ref_iterator(it, filter);
diff --git a/reftable/record.c b/reftable/record.c
index 672c5f909a9..fb5652ed575 100644
--- a/reftable/record.c
+++ b/reftable/record.c
@@ -102,7 +102,9 @@ static int decode_string(struct reftable_buf *dest, struct string_view in)
 {
 	int start_len = in.len;
 	uint64_t tsize = 0;
-	int n = get_var_int(&tsize, &in);
+	int n, err;
+
+	n = get_var_int(&tsize, &in);
 	if (n <= 0)
 		return -1;
 	string_view_consume(&in, n);
@@ -110,7 +112,10 @@ static int decode_string(struct reftable_buf *dest, struct string_view in)
 		return -1;
 
 	reftable_buf_reset(dest);
-	reftable_buf_add(dest, in.buf, tsize);
+	err = reftable_buf_add(dest, in.buf, tsize);
+	if (err < 0)
+		return err;
+
 	string_view_consume(&in, tsize);
 
 	return start_len - in.len;
@@ -189,7 +194,7 @@ int reftable_decode_key(struct reftable_buf *last_key, uint8_t *extra,
 	int start_len = in.len;
 	uint64_t prefix_len = 0;
 	uint64_t suffix_len = 0;
-	int n;
+	int err, n;
 
 	n = reftable_decode_keylen(in, &prefix_len, &suffix_len, extra);
 	if (n < 0)
@@ -200,8 +205,14 @@ int reftable_decode_key(struct reftable_buf *last_key, uint8_t *extra,
 	    prefix_len > last_key->len)
 		return -1;
 
-	reftable_buf_setlen(last_key, prefix_len);
-	reftable_buf_add(last_key, in.buf, suffix_len);
+	err = reftable_buf_setlen(last_key, prefix_len);
+	if (err < 0)
+		return err;
+
+	err = reftable_buf_add(last_key, in.buf, suffix_len);
+	if (err < 0)
+		return err;
+
 	string_view_consume(&in, suffix_len);
 
 	return start_len - in.len;
@@ -1047,9 +1058,12 @@ static int reftable_index_record_copy_from(void *rec, const void *src_rec,
 {
 	struct reftable_index_record *dst = rec;
 	const struct reftable_index_record *src = src_rec;
+	int err;
 
 	reftable_buf_reset(&dst->last_key);
-	reftable_buf_add(&dst->last_key, src->last_key.buf, src->last_key.len);
+	err = reftable_buf_add(&dst->last_key, src->last_key.buf, src->last_key.len);
+	if (err < 0)
+		return err;
 	dst->offset = src->offset;
 
 	return 0;
@@ -1090,10 +1104,12 @@ static int reftable_index_record_decode(void *rec, struct reftable_buf key,
 {
 	struct string_view start = in;
 	struct reftable_index_record *r = rec;
-	int n = 0;
+	int err, n = 0;
 
 	reftable_buf_reset(&r->last_key);
-	reftable_buf_add(&r->last_key, key.buf, key.len);
+	err = reftable_buf_add(&r->last_key, key.buf, key.len);
+	if (err < 0)
+		return err;
 
 	n = get_var_int(&r->offset, &in);
 	if (n < 0)
diff --git a/reftable/stack.c b/reftable/stack.c
index 243b10715cc..c33979536ef 100644
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -78,8 +78,9 @@ int reftable_new_stack(struct reftable_stack **dest, const char *dir,
 	*dest = NULL;
 
 	reftable_buf_reset(&list_file_name);
-	reftable_buf_addstr(&list_file_name, dir);
-	reftable_buf_addstr(&list_file_name, "/tables.list");
+	if ((err = reftable_buf_addstr(&list_file_name, dir)) < 0 ||
+	    (err = reftable_buf_addstr(&list_file_name, "/tables.list")) < 0)
+		goto out;
 
 	p->list_file = reftable_buf_detach(&list_file_name);
 	p->list_fd = -1;
@@ -747,12 +748,14 @@ int reftable_addition_commit(struct reftable_addition *add)
 		goto done;
 
 	for (i = 0; i < add->stack->merged->readers_len; i++) {
-		reftable_buf_addstr(&table_list, add->stack->readers[i]->name);
-		reftable_buf_addstr(&table_list, "\n");
+		if ((err = reftable_buf_addstr(&table_list, add->stack->readers[i]->name)) < 0 ||
+		    (err = reftable_buf_addstr(&table_list, "\n")) < 0)
+			goto done;
 	}
 	for (i = 0; i < add->new_tables_len; i++) {
-		reftable_buf_addstr(&table_list, add->new_tables[i]);
-		reftable_buf_addstr(&table_list, "\n");
+		if ((err = reftable_buf_addstr(&table_list, add->new_tables[i])) < 0 ||
+		    (err = reftable_buf_addstr(&table_list, "\n")) < 0)
+			goto done;
 	}
 
 	err = write_in_full(lock_file_fd, table_list.buf, table_list.len);
@@ -867,7 +870,10 @@ int reftable_addition_add(struct reftable_addition *add,
 	err = stack_filename(&temp_tab_file_name, add->stack, next_name.buf);
 	if (err < 0)
 		goto done;
-	reftable_buf_addstr(&temp_tab_file_name, ".temp.XXXXXX");
+
+	err = reftable_buf_addstr(&temp_tab_file_name, ".temp.XXXXXX");
+	if (err < 0)
+		goto done;
 
 	tab_file = mks_tempfile(temp_tab_file_name.buf);
 	if (!tab_file) {
@@ -914,7 +920,10 @@ int reftable_addition_add(struct reftable_addition *add,
 	err = format_name(&next_name, wr->min_update_index, wr->max_update_index);
 	if (err < 0)
 		goto done;
-	reftable_buf_addstr(&next_name, ".ref");
+
+	err = reftable_buf_addstr(&next_name, ".ref");
+	if (err < 0)
+		goto done;
 
 	err = stack_filename(&tab_file_name, add->stack, next_name.buf);
 	if (err < 0)
@@ -975,7 +984,10 @@ static int stack_compact_locked(struct reftable_stack *st,
 	err = stack_filename(&tab_file_path, st, next_name.buf);
 	if (err < 0)
 		goto done;
-	reftable_buf_addstr(&tab_file_path, ".temp.XXXXXX");
+
+	err = reftable_buf_addstr(&tab_file_path, ".temp.XXXXXX");
+	if (err < 0)
+		goto done;
 
 	tab_file = mks_tempfile(tab_file_path.buf);
 	if (!tab_file) {
@@ -1404,7 +1416,9 @@ static int stack_compact_range(struct reftable_stack *st,
 		if (err < 0)
 			goto done;
 
-		reftable_buf_addstr(&new_table_name, ".ref");
+		err = reftable_buf_addstr(&new_table_name, ".ref");
+		if (err < 0)
+			goto done;
 
 		err = stack_filename(&new_table_path, st, new_table_name.buf);
 		if (err < 0)
@@ -1423,16 +1437,19 @@ static int stack_compact_range(struct reftable_stack *st,
 	 * simply skip writing it.
 	 */
 	for (i = 0; i < first_to_replace; i++) {
-		reftable_buf_addstr(&tables_list_buf, names[i]);
-		reftable_buf_addstr(&tables_list_buf, "\n");
+		if ((err = reftable_buf_addstr(&tables_list_buf, names[i])) < 0 ||
+		    (err = reftable_buf_addstr(&tables_list_buf, "\n")) < 0)
+		      goto done;
 	}
 	if (!is_empty_table) {
-		reftable_buf_addstr(&tables_list_buf, new_table_name.buf);
-		reftable_buf_addstr(&tables_list_buf, "\n");
+		if ((err = reftable_buf_addstr(&tables_list_buf, new_table_name.buf)) < 0 ||
+		    (err = reftable_buf_addstr(&tables_list_buf, "\n")) < 0)
+			goto done;
 	}
 	for (i = last_to_replace + 1; names[i]; i++) {
-		reftable_buf_addstr(&tables_list_buf, names[i]);
-		reftable_buf_addstr(&tables_list_buf, "\n");
+		if ((err = reftable_buf_addstr(&tables_list_buf, names[i])) < 0 ||
+		    (err = reftable_buf_addstr(&tables_list_buf, "\n")) < 0)
+			goto done;
 	}
 
 	err = write_in_full(get_lock_file_fd(&tables_list_lock),
diff --git a/reftable/writer.c b/reftable/writer.c
index 377db709c85..fd136794d5a 100644
--- a/reftable/writer.c
+++ b/reftable/writer.c
@@ -217,6 +217,7 @@ static int writer_index_hash(struct reftable_writer *w, struct reftable_buf *has
 	node = tree_search(w->obj_index_tree, &want, &obj_index_tree_node_compare);
 	if (!node) {
 		struct obj_index_tree_node empty = OBJ_INDEX_TREE_NODE_INIT;
+		int err;
 
 		key = reftable_malloc(sizeof(*key));
 		if (!key)
@@ -225,7 +226,9 @@ static int writer_index_hash(struct reftable_writer *w, struct reftable_buf *has
 		*key = empty;
 
 		reftable_buf_reset(&key->hash);
-		reftable_buf_add(&key->hash, hash->buf, hash->len);
+		err = reftable_buf_add(&key->hash, hash->buf, hash->len);
+		if (err < 0)
+			return err;
 		tree_insert(&w->obj_index_tree, key,
 			    &obj_index_tree_node_compare);
 	} else {
@@ -259,7 +262,10 @@ static int writer_add_record(struct reftable_writer *w,
 	}
 
 	reftable_buf_reset(&w->last_key);
-	reftable_buf_add(&w->last_key, key.buf, key.len);
+	err = reftable_buf_add(&w->last_key, key.buf, key.len);
+	if (err < 0)
+		goto done;
+
 	if (!w->block_writer) {
 		err = writer_reinit_block_writer(w, reftable_record_type(rec));
 		if (err < 0)
@@ -334,8 +340,10 @@ int reftable_writer_add_ref(struct reftable_writer *w,
 		goto out;
 
 	if (!w->opts.skip_index_objects && reftable_ref_record_val1(ref)) {
-		reftable_buf_add(&buf, (char *)reftable_ref_record_val1(ref),
-			   hash_size(w->opts.hash_id));
+		err = reftable_buf_add(&buf, (char *)reftable_ref_record_val1(ref),
+				       hash_size(w->opts.hash_id));
+		if (err < 0)
+			goto out;
 
 		err = writer_index_hash(w, &buf);
 		if (err < 0)
@@ -344,8 +352,10 @@ int reftable_writer_add_ref(struct reftable_writer *w,
 
 	if (!w->opts.skip_index_objects && reftable_ref_record_val2(ref)) {
 		reftable_buf_reset(&buf);
-		reftable_buf_add(&buf, reftable_ref_record_val2(ref),
-			   hash_size(w->opts.hash_id));
+		err = reftable_buf_add(&buf, reftable_ref_record_val2(ref),
+				       hash_size(w->opts.hash_id));
+		if (err < 0)
+			goto out;
 
 		err = writer_index_hash(w, &buf);
 		if (err < 0)
@@ -407,17 +417,27 @@ int reftable_writer_add_log(struct reftable_writer *w,
 
 	input_log_message = log->value.update.message;
 	if (!w->opts.exact_log_message && log->value.update.message) {
-		reftable_buf_addstr(&cleaned_message, log->value.update.message);
+		err = reftable_buf_addstr(&cleaned_message, log->value.update.message);
+		if (err < 0)
+			goto done;
+
 		while (cleaned_message.len &&
-		       cleaned_message.buf[cleaned_message.len - 1] == '\n')
-			reftable_buf_setlen(&cleaned_message,
-				      cleaned_message.len - 1);
+		       cleaned_message.buf[cleaned_message.len - 1] == '\n') {
+			err = reftable_buf_setlen(&cleaned_message,
+						  cleaned_message.len - 1);
+			if (err < 0)
+				goto done;
+		}
 		if (strchr(cleaned_message.buf, '\n')) {
 			/* multiple lines not allowed. */
 			err = REFTABLE_API_ERROR;
 			goto done;
 		}
-		reftable_buf_addstr(&cleaned_message, "\n");
+
+		err = reftable_buf_addstr(&cleaned_message, "\n");
+		if (err < 0)
+			goto done;
+
 		log->value.update.message = cleaned_message.buf;
 	}
 
@@ -781,8 +801,10 @@ static int writer_flush_nonempty_block(struct reftable_writer *w)
 
 	index_record.offset = w->next;
 	reftable_buf_reset(&index_record.last_key);
-	reftable_buf_add(&index_record.last_key, w->block_writer->last_key.buf,
-		   w->block_writer->last_key.len);
+	err = reftable_buf_add(&index_record.last_key, w->block_writer->last_key.buf,
+			       w->block_writer->last_key.len);
+	if (err < 0)
+		return err;
 	w->index[w->index_len] = index_record;
 	w->index_len++;
 
