diff --git a/accelerator/errors.h b/accelerator/errors.h
index c399b89f..72f95924 100644
--- a/accelerator/errors.h
+++ b/accelerator/errors.h
@@ -94,7 +94,7 @@ typedef enum {
   /**< NULL object in serializer */
   SC_SERIALIZER_JSON_PARSE = 0x03 | SC_MODULE_SERIALIZER | SC_SEVERITY_FATAL,
   /**< Fail to parse JSON object in serializer */
-  SC_SERIALIZER_JSON_PARSE_UNICODE =
+  SC_SERIALIZER_JSON_PARSE_ASCII =
       0x04 | SC_MODULE_SERIALIZER | SC_SEVERITY_FATAL,
   /**< unicode value in JSON */
   SC_SERIALIZER_INVALID_REQ = 0x05 | SC_MODULE_SERIALIZER | SC_SEVERITY_FATAL,
diff --git a/serializer/serializer.c b/serializer/serializer.c
index a11bf55c..3c0ad7eb 100644
--- a/serializer/serializer.c
+++ b/serializer/serializer.c
@@ -316,6 +316,13 @@ status_t ta_send_transfer_req_deserialize(const char* const obj,
   if (json_result != NULL && json_result->valuestring != NULL) {
     tag_len = strnlen(json_result->valuestring, NUM_TRYTES_TAG);
 
+    for (int i = 0; i < tag_len; i++) {
+      if (json_result->valuestring[i] & (unsigned)128) {
+        ret = SC_SERIALIZER_JSON_PARSE_ASCII;
+        goto done;
+      }
+    }
+
     // If 'tag' is less than 27 trytes (NUM_TRYTES_TAG), expands it
     if (tag_len < NUM_TRYTES_TAG) {
       char new_tag[NUM_TRYTES_TAG + 1];
@@ -624,9 +631,10 @@ status_t send_mam_req_deserialize(const char* const obj, send_mam_req_t* req) {
 
     // in case the payload is unicode, char more than 128 will result to an
     // error status_t code
-    for (int i = 0; i < strlen(json_result->valuestring); i++) {
+    size_t payload_ascii_len = payload_size > 1;
+    for (int i = 0; i < payload_ascii_len; i++) {
       if (json_result->valuestring[i] & (unsigned)128) {
-        ret = SC_SERIALIZER_JSON_PARSE_UNICODE;
+        ret = SC_SERIALIZER_JSON_PARSE_ASCII;
         goto done;
       }
     }
diff --git a/tests/regression/runner.py b/tests/regression/runner.py
index dcfc0cf7..6385987f 100644
--- a/tests/regression/runner.py
+++ b/tests/regression/runner.py
@@ -269,7 +269,7 @@ def test_send_transfer(self):
                           response[i]["content"] + ", status code = " +
                           response[i]["status_code"])
 
-        pass_case = [0, 1, 2, 3]
+        pass_case = [0, 1, 2, 3, 5, 6, 7, 8, 9, 10]
         for i in range(len(response)):
             if i in pass_case:
                 res_json = json.loads(response[i]["content"])
@@ -290,7 +290,7 @@ def test_send_transfer(self):
                     valid_trytes(res_json["signature_and_message_fragment"],
                                  LEN_MSG_SIGN))
             elif i == 4:
-                self.assertEqual(EMPTY_REPLY, response[i]["status_code"])
+                self.assertEqual(STATUS_CODE_500, response[i]["status_code"])
             else:
                 self.assertEqual(STATUS_CODE_404, response[i]["status_code"])
 
diff --git a/tests/test_define.h b/tests/test_define.h
index f095790d..edb6d46d 100644
--- a/tests/test_define.h
+++ b/tests/test_define.h
@@ -18,8 +18,8 @@ extern "C" {
   "RVORZ9SIIP9RCYMREUIXXVPQIPHVCNPQ9HZWYKFWYWZRE9JQKG9REPKIASHUUECPSQO9JT9XNM" \
   "VKWYGVA"
 #define TRYTES_81_3                                                            \
-  "FPPBU9AOXZHSJEWDCPWGCPKGOVIUWWPDTIIXDJUKYYNNPTWCGDWFBZLKVCLOKGYEHJUMABSTA9" \
-  "OP99999"
+  "BGBQJCVSOESTAVKHKD9QBNYVHUUEQUGZ9BEUAPG9HGQWAHMDAJXKDPUZPRBZVVIPRHMERPOBCD" \
+  "YB99999"
 #define BUNDLE_HASH                                                            \
   "LVXEVZABVCIFEDSCONKEVEYBSIRMXGHLJDKSKQHTKZC9ULEAPSLKOOWCCZJGWSIISDDSEVUQHV" \
   "GPFOSIW"