diff --git a/src/index/elastic.c b/src/index/elastic.c
index 6da4079..61eb166 100644
--- a/src/index/elastic.c
+++ b/src/index/elastic.c
@@ -52,11 +52,22 @@ void index_json_func(void *arg) {
     elastic_index_line(line);
 }
 
+void delete_document(const char* document_id_str, void* UNUSED(_data)) {
+    size_t id_len = strlen(document_id_str);
+    es_bulk_line_t *bulk_line = malloc(sizeof(es_bulk_line_t));
+    bulk_line->type = ES_BULK_LINE_DELETE;
+    bulk_line->next = NULL;
+    memcpy(bulk_line->path_md5_str, document_id_str, MD5_STR_LENGTH);
+    tpool_add_work(IndexCtx.pool, index_json_func, bulk_line);
+}
+
+
 void index_json(cJSON *document, const char index_id_str[MD5_STR_LENGTH]) {
     char *json = cJSON_PrintUnformatted(document);
 
     size_t json_len = strlen(json);
     es_bulk_line_t *bulk_line = malloc(sizeof(es_bulk_line_t) + json_len + 2);
+    bulk_line->type = ES_BULK_LINE_INDEX;
     memcpy(bulk_line->line, json, json_len);
     memcpy(bulk_line->path_md5_str, index_id_str, MD5_STR_LENGTH);
     *(bulk_line->line + json_len) = '\n';
@@ -67,11 +78,6 @@ void index_json(cJSON *document, const char index_id_str[MD5_STR_LENGTH]) {
     tpool_add_work(IndexCtx.pool, index_json_func, bulk_line);
 }
 
-void delete_document(const char* document_id_str, void* data) {
-    const char* index_id_str = data;
-    // TODO bulk delete
-}
-
 void execute_update_script(const char *script, int async, const char index_id[MD5_STR_LENGTH]) {
 
     if (Indexer == NULL) {
@@ -130,30 +136,47 @@ void *create_bulk_buffer(int max, int *count, size_t *buf_len) {
     size_t buf_cur = 0;
     char *buf = malloc(8192);
     size_t buf_capacity = 8192;
+#define GROW_BUF(delta)                       \
+    while (buf_size + (delta) > buf_capacity) { \
+      buf_capacity *= 2;                        \
+      buf = realloc(buf, buf_capacity);         \
+    }                                           \
+    buf_size += (delta);                        \
 
+    // see: https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-bulk.html
+    // ES_BULK_LINE_INDEX: two lines, 1st action, 2nd content
+    // ES_BULK_LINE_DELETE: one line
     while (line != NULL && *count < max) {
         char action_str[256];
-        snprintf(
-                action_str, sizeof(action_str),
-                "{\"index\":{\"_id\":\"%s\",\"_type\":\"_doc\",\"_index\":\"%s\"}}\n",
-                line->path_md5_str, Indexer->es_index
-        );
+        if (line->type == ES_BULK_LINE_INDEX) {
+            snprintf(
+                    action_str, sizeof(action_str),
+                    "{\"index\":{\"_id\":\"%s\",\"_type\":\"_doc\",\"_index\":\"%s\"}}\n",
+                    line->path_md5_str, Indexer->es_index
+            );
 
-        size_t action_str_len = strlen(action_str);
-        size_t line_len = strlen(line->line);
+            size_t action_str_len = strlen(action_str);
+            size_t line_len = strlen(line->line);
 
-        while (buf_size + line_len + action_str_len > buf_capacity) {
-            buf_capacity *= 2;
-            buf = realloc(buf, buf_capacity);
+            GROW_BUF(action_str_len + line_len);
+
+            memcpy(buf + buf_cur, action_str, action_str_len);
+            buf_cur += action_str_len;
+            memcpy(buf + buf_cur, line->line, line_len);
+            buf_cur += line_len;
+
+        } else if (line->type == ES_BULK_LINE_DELETE) {
+            snprintf(
+                    action_str, sizeof(action_str),
+                    "{\"delete\":{\"_id\":\"%s\",\"_index\":\"%s\"}}\n",
+                    line->path_md5_str, Indexer->es_index
+            );
+
+            size_t action_str_len = strlen(action_str);
+            GROW_BUF(action_str_len);
+            memcpy(buf + buf_cur, action_str, action_str_len);
+            buf_cur += action_str_len;
         }
-
-        buf_size += line_len + action_str_len;
-
-        memcpy(buf + buf_cur, action_str, action_str_len);
-        buf_cur += action_str_len;
-        memcpy(buf + buf_cur, line->line, line_len);
-        buf_cur += line_len;
-
         line = line->next;
         (*count)++;
     }
diff --git a/src/index/elastic.h b/src/index/elastic.h
index 65cfc6c..5a33d15 100644
--- a/src/index/elastic.h
+++ b/src/index/elastic.h
@@ -3,9 +3,13 @@
 
 #include "src/sist.h"
 
+#define ES_BULK_LINE_INDEX 0
+#define ES_BULK_LINE_DELETE 1
+
 typedef struct es_bulk_line {
     struct es_bulk_line *next;
     char path_md5_str[MD5_STR_LENGTH];
+    int type;
     char line[0];
 } es_bulk_line_t;
 
diff --git a/src/main.c b/src/main.c
index 5b8cd88..3bb9401 100644
--- a/src/main.c
+++ b/src/main.c
@@ -489,7 +489,7 @@ void sist2_index(index_args_t *args) {
     snprintf(file_path, PATH_MAX, "%s_index_delete.list.zst", args->index_path);
     if (0 == access(file_path, R_OK)) {
         read_lines(file_path, (line_processor_t) {
-            .data = desc.id,
+            .data = NULL,
             .func = delete_document
         });
         LOG_DEBUGF("main.c", "Read index file %s (%s)", file_path, desc.type)
@@ -698,7 +698,7 @@ int main(int argc, const char *argv[]) {
     exec_args->async_script = common_async_script;
     index_args->async_script = common_async_script;
 
-    scan_args->incremental = common_incremental;
+    scan_args->incremental = (common_incremental == NULL) ? NULL : strdup(common_incremental);
     index_args->incremental = (common_incremental != NULL);
 
     if (argc == 0) {