diff --git a/include/cc_bstring.h b/include/cc_bstring.h
index 18cfda558..86c1aadb7 100644
--- a/include/cc_bstring.h
+++ b/include/cc_bstring.h
@@ -170,6 +170,7 @@ void bstring_free(struct bstring **bstring);
 
 /* bstring to uint conversion */
 rstatus_i bstring_atou64(uint64_t *u64, struct bstring *str);
+rstatus_i bstring_atoi64(int64_t *i64, struct bstring *str);
 
 #ifdef __cplusplus
 }
diff --git a/src/cc_bstring.c b/src/cc_bstring.c
index efa51949f..68374423c 100644
--- a/src/cc_bstring.c
+++ b/src/cc_bstring.c
@@ -113,6 +113,46 @@ bstring_compare(const struct bstring *s1, const struct bstring *s2)
     return cc_bcmp(s1->data, s2->data, s1->len);
 }
 
+rstatus_i
+bstring_atoi64(int64_t *i64, struct bstring *str)
+{
+    uint32_t offset = 0;
+    uint8_t c;
+    int64_t sign = 1;
+
+    if (str->len == 0 || str->len >= CC_INT64_MAXLEN) {
+        return CC_ERROR;
+    }
+
+    if (*str->data == '-') {
+        offset = 1;
+        sign = -1;
+    }
+
+    for (*i64 = 0LL; offset < str->len; offset++) {
+        c = *(str->data + offset);
+        if (c < '0' || c > '9') {
+            return CC_ERROR;
+        }
+
+        // overflow check
+        if (offset == CC_INT64_MAXLEN - 2) {
+            if (sign < 0 && *i64 == INT64_MIN / 10 &&
+                    c - '0' > (uint64_t)(-INT64_MIN) % 10) {
+                return CC_ERROR;
+            }
+            if (sign > 0 && *i64 == INT64_MAX / 10 &&
+                    c - '0' > INT64_MAX % 10) {
+                return CC_ERROR;
+            }
+        }
+
+        *i64 = *i64 * 10LL + sign * (int64_t)(c - '0');
+    }
+
+    return CC_OK;
+}
+
 rstatus_i
 bstring_atou64(uint64_t *u64, struct bstring *str)
 {
diff --git a/test/bstring/check_bstring.c b/test/bstring/check_bstring.c
index 313e7196b..e35fa61aa 100644
--- a/test/bstring/check_bstring.c
+++ b/test/bstring/check_bstring.c
@@ -119,6 +119,37 @@ START_TEST(test_strcmp)
 END_TEST
 
 
+START_TEST(test_atoi64)
+{
+    int64_t val;
+    struct bstring bstr;
+    char int64[CC_INT64_MAXLEN];
+
+    test_reset();
+
+    ck_assert_int_eq(bstring_atoi64(&val, &str2bstr("foo")), CC_ERROR);
+
+    ck_assert_int_eq(bstring_atoi64(&val, &str2bstr("123")), CC_OK);
+    ck_assert_uint_eq(val, 123);
+    ck_assert_int_eq(bstring_atoi64(&val, &str2bstr("-123")), CC_OK);
+    ck_assert_uint_eq(val, -123);
+
+    sprintf(int64, "%"PRIi64, INT64_MAX);
+    bstring_init(&bstr);
+    ck_assert_int_eq(bstring_copy(&bstr, int64, strlen(int64)), CC_OK);
+    ck_assert_int_eq(bstring_atoi64(&val, &bstr), CC_OK);
+    ck_assert_int_eq(val, INT64_MAX);
+    bstring_deinit(&bstr);
+
+    sprintf(int64, "%"PRIi64, INT64_MIN);
+    bstring_init(&bstr);
+    ck_assert_int_eq(bstring_copy(&bstr, int64, strlen(int64)), CC_OK);
+    ck_assert_int_eq(bstring_atoi64(&val, &bstr), CC_OK);
+    ck_assert_int_eq(val, INT64_MIN);
+    bstring_deinit(&bstr);
+}
+END_TEST
+
 START_TEST(test_atou64)
 {
     uint64_t val;
@@ -189,6 +220,7 @@ bstring_suite(void)
     tcase_add_test(tc_bstring, test_copy);
     tcase_add_test(tc_bstring, test_compare);
     tcase_add_test(tc_bstring, test_strcmp);
+    tcase_add_test(tc_bstring, test_atoi64);
     tcase_add_test(tc_bstring, test_atou64);
     tcase_add_test(tc_bstring, test_bstring_alloc_and_free);