diff --git a/src/validators/domain.py b/src/validators/domain.py
index a8f991c4..c5eea7d4 100644
--- a/src/validators/domain.py
+++ b/src/validators/domain.py
@@ -42,7 +42,8 @@ def domain(value: str, /, *, rfc_1034: bool = False, rfc_2782: bool = False):
             # First character of the domain
             rf"^(?:[a-zA-Z0-9{'_'if rfc_2782 else ''}]"
             # Sub domain + hostname
-            + rf"(?:[a-zA-Z0-9-_]{{0,61}}[A-Za-z0-9{'_'if rfc_2782 else ''}])?\.)"
+            + rf"(?:[a-zA-Z0-9-{'_'if rfc_2782 else ''}]{{0,61}}"
+            + rf"[A-Za-z0-9{'_'if rfc_2782 else ''}])?\.)"
             # First 61 characters of the gTLD
             + r"+[A-Za-z0-9][A-Za-z0-9-_]{0,61}"
             # Last character of the gTLD
diff --git a/tests/test_domain.py b/tests/test_domain.py
index 4cd9c658..c8f5c4d9 100644
--- a/tests/test_domain.py
+++ b/tests/test_domain.py
@@ -11,8 +11,9 @@
     ("value", "rfc_1034", "rfc_2782"),
     [
         ("example.com", False, False),
+        ("exa_mple.com", False, True),
         ("xn----gtbspbbmkef.xn--p1ai", False, False),
-        ("underscore_subdomain.example.com", False, False),
+        ("underscore_subdomain.example.com", False, True),
         ("something.versicherung", False, False),
         ("someThing.versicherung.", True, False),
         ("11.com", False, False),