diff --git a/plugins/restful/adapter_handle.c b/plugins/restful/adapter_handle.c
index 465d2bcbb..0a7bc9683 100644
--- a/plugins/restful/adapter_handle.c
+++ b/plugins/restful/adapter_handle.c
@@ -550,6 +550,7 @@ static int json_to_gdatatags(neu_json_gtag_array_t *gtag_array,
             gdatatags[i].tags[j].bias    = gtag_array->gtags[i].tags[j].bias;
             gdatatags[i].tags[j].address = gtag_array->gtags[i].tags[j].address;
             gdatatags[i].tags[j].name    = gtag_array->gtags[i].tags[j].name;
+            gdatatags[i].tags[j].unit    = gtag_array->gtags[i].tags[j].unit;
             if (gtag_array->gtags[i].tags[j].description != NULL) {
                 gdatatags[i].tags[j].description =
                     gtag_array->gtags[i].tags[j].description;
@@ -560,6 +561,7 @@ static int json_to_gdatatags(neu_json_gtag_array_t *gtag_array,
             gtag_array->gtags[i].tags[j].address     = NULL; // moved
             gtag_array->gtags[i].tags[j].name        = NULL; // moved
             gtag_array->gtags[i].tags[j].description = NULL; // moved
+            gtag_array->gtags[i].tags[j].unit        = NULL; // moved
         }
     }
 
diff --git a/plugins/restful/global_config_handle.c b/plugins/restful/global_config_handle.c
index 4ff798b58..7467fcd53 100644
--- a/plugins/restful/global_config_handle.c
+++ b/plugins/restful/global_config_handle.c
@@ -1229,10 +1229,12 @@ static int get_driver_tags_resp(context_t *ctx, neu_resp_get_tag_t *tags)
         gtag->tags[index].precision   = tag->precision;
         gtag->tags[index].decimal     = tag->decimal;
         gtag->tags[index].bias        = tag->bias;
+        gtag->tags[index].unit        = tag->unit;
         gtag->tags[index].t           = NEU_JSON_UNDEFINE;
         tag->name                     = NULL; // moved
         tag->address                  = NULL; // moved
         tag->description              = NULL; // moved
+        tag->unit                     = NULL; // moved
     }
 
 end:
@@ -1501,9 +1503,10 @@ static int add_tag(context_t *ctx, neu_json_add_tags_req_t *data)
         cmd.tags[i].name      = strdup(data->tags[i].name);
         cmd.tags[i].description =
             strdup(data->tags[i].description ? data->tags[i].description : "");
+        cmd.tags[i].unit = strdup(data->tags[i].unit ? data->tags[i].unit : "");
 
         if (NULL == cmd.tags[i].address || NULL == cmd.tags[i].name ||
-            NULL == cmd.tags[i].description) {
+            NULL == cmd.tags[i].description || NULL == cmd.tags[i].unit) {
             ret = NEU_ERR_EINTERNAL;
             goto error;
         }
@@ -1517,7 +1520,7 @@ static int add_tag(context_t *ctx, neu_json_add_tags_req_t *data)
     return ret;
 
 error:
-    for (int j = 0; j < i && j < cmd.n_tag; ++j) {
+    for (int j = 0; j < cmd.n_tag; ++j) {
         neu_tag_fini(&cmd.tags[j]);
     }
     free(cmd.tags);
diff --git a/tests/ft/http_api/test_http_api.py b/tests/ft/http_api/test_http_api.py
index db1cce083..91af4f6b8 100644
--- a/tests/ft/http_api/test_http_api.py
+++ b/tests/ft/http_api/test_http_api.py
@@ -292,6 +292,77 @@ def test_get_global_config(self):
         for node in global_config['nodes']:
             api.del_node(node['name'])
 
+    @pytest.mark.parametrize("unit", ["°C", "", None], ids=["nonempty", "empty", "missing"])
+    def test_global_config_tag_unit_roundtrip(self, unit):
+        driver = copy.deepcopy(driver_1)
+        group = driver["groups"][0]
+        tags = group["tags"]
+        if unit is None:
+            tags[0].pop("unit")
+        else:
+            tags[0]["unit"] = unit
+        tags[1].pop("unit")
+        expected_tags = copy.deepcopy(tags)
+        for tag in expected_tags:
+            tag.setdefault("unit", "")
+
+        data = {
+            "nodes": [{"name": driver["name"], "plugin": driver["plugin"]}],
+            "groups": [{"driver": driver["name"], "group": group["group"],
+                        "interval": group["interval"], "tag_count": len(tags)}],
+            "tags": [{"driver": driver["name"], "group": group["group"], "tags": tags}],
+            "subscriptions": [],
+            "settings": []
+        }
+        try:
+            for _ in range(2):
+                response = api.put_global_config(json=data)
+                assert 200 == response.status_code
+                assert error.NEU_ERR_SUCCESS == response.json()["error"]
+
+                response = api.get_tags(driver["name"], group["group"])
+                assert 200 == response.status_code
+                assert expected_tags == response.json()["tags"]
+
+                response = api.get_global_config()
+                assert 200 == response.status_code
+                data = response.json()
+                exported = next(g for g in data["tags"]
+                                if g["driver"] == driver["name"] and g["group"] == group["group"])
+                assert expected_tags == exported["tags"]
+        finally:
+            api.del_node(driver["name"])
+
+    @pytest.mark.parametrize("unit", ["°C", "", None], ids=["nonempty", "empty", "missing"])
+    def test_driver_tag_unit_roundtrip(self, unit):
+        driver = copy.deepcopy(driver_1)
+        tags = driver["groups"][0]["tags"]
+        if unit is None:
+            tags[0].pop("unit")
+        else:
+            tags[0]["unit"] = unit
+        tags[1].pop("unit")
+        expected = copy.deepcopy(driver)
+        for tag in expected["groups"][0]["tags"]:
+            tag.setdefault("unit", "")
+
+        try:
+            for _ in range(2):
+                response = api.put_drivers([driver])
+                assert 200 == response.status_code
+                assert error.NEU_ERR_SUCCESS == response.json()["error"]
+
+                response = api.get_tags(driver["name"], driver["groups"][0]["group"])
+                assert 200 == response.status_code
+                assert expected["groups"][0]["tags"] == response.json()["tags"]
+
+                response = api.get_driver(driver["name"])
+                assert 200 == response.status_code
+                assert [expected] == response.json()["nodes"]
+                driver = response.json()["nodes"][0]
+        finally:
+            api.del_node(driver["name"])
+
     @description(given="running neuron", when="put drivers with too long node name", then="should fail")
     def test_put_drivers_with_long_node_name(self):
         response = api.put_driver(