diff --git a/common/birdxplorer_common/models.py b/common/birdxplorer_common/models.py
index fcd6119..28e74f0 100644
--- a/common/birdxplorer_common/models.py
+++ b/common/birdxplorer_common/models.py
@@ -134,15 +134,17 @@ class UpToNineteenDigitsDecimalString(BaseString):
     Traceback (most recent call last):
      ...
     pydantic_core._pydantic_core.ValidationError: 1 validation error for function-after[validate(), constrained-str]
-      String should match pattern '^([0-9]{19}|)$' [type=string_pattern_mismatch, input_value='test', input_type=str]
+      String should match pattern '^([0-9]{18,19}|)$' [type=string_pattern_mismatch, input_value='test', input_type=str]
      ...
     >>> UpToNineteenDigitsDecimalString.from_str("1234567890123456789")
     UpToNineteenDigitsDecimalString('1234567890123456789')
+    >>> UpToNineteenDigitsDecimalString.from_str("123456789012345678")
+    UpToNineteenDigitsDecimalString('123456789012345678')
     """
 
     @classmethod
     def __get_extra_constraint_dict__(cls) -> dict[str, Any]:
-        return dict(super().__get_extra_constraint_dict__(), pattern=r"^([0-9]{19}|)$")
+        return dict(super().__get_extra_constraint_dict__(), pattern=r"^([0-9]{18,19}|)$")
 
 
 class NonEmptyStringMixin(BaseString):