diff --git a/src/scverse_misc/_deprecated.py b/src/scverse_misc/_deprecated.py
index c13b65f..1076491 100644
--- a/src/scverse_misc/_deprecated.py
+++ b/src/scverse_misc/_deprecated.py
@@ -2,6 +2,7 @@
 
 import sys
 from inspect import getdoc
+from textwrap import indent
 from typing import TYPE_CHECKING, LiteralString
 
 if sys.version_info >= (3, 13):
@@ -54,13 +55,15 @@ def _deprecated_at[F: Callable[..., object]](
 
     def decorate(func: F) -> F:
         kind = "function" if func.__name__ == func.__qualname__ else "method"
-        warnmsg = f"The {kind} {func.__name__} is deprecated and will be removed in the future."
+        warnmsg = f"The {kind} {func.__name__} is deprecated and will be removed in the future"
 
         doc = getdoc(func)
         docmsg = f".. version-deprecated:: {msg.version_deprecated}"
         if len(msg):
-            docmsg += f"\n   {msg}"
-            warnmsg += f" {msg}"
+            docmsg += f"\n{indent(msg, 3 * ' ')}"
+            warnmsg += f". {msg}" if msg.count("\n") == 0 else f":\n{indent(msg, 4 * ' ')}"
+        else:
+            warnmsg += "."
 
         if doc is None:
             doc = docmsg
diff --git a/tests/test_deprecation_decorator.py b/tests/test_deprecation_decorator.py
index 9ecea5c..097e631 100644
--- a/tests/test_deprecation_decorator.py
+++ b/tests/test_deprecation_decorator.py
@@ -6,7 +6,13 @@
 from scverse_misc import Deprecation, deprecated
 
 
-@pytest.fixture(params=[pytest.param(None, id="no_message"), pytest.param("Test message.", id="message")])
+@pytest.fixture(
+    params=[
+        pytest.param(None, id="no_message"),
+        pytest.param("Test message.", id="short_message"),
+        pytest.param("Test\nmessage.", id="long_message"),
+    ]
+)
 def msg(request: pytest.FixtureRequest) -> str | None:
     return cast(str | None, request.param)
 
@@ -52,14 +58,17 @@ def test_deprecation_decorator(
 
     assert deprecated_func.__doc__ is not None
     lines = deprecated_func.__doc__.expandtabs().splitlines()
-    if docstring is None:
-        assert lines[0].startswith(".. version-deprecated::")
-    else:
+    offset = 0 if docstring is None else 2
+
+    if docstring is not None:
         lines_orig = docstring.expandtabs().splitlines()
         assert lines[0] == lines_orig[0]
-        assert len(lines[1].strip()) == 0
-        assert lines[2].startswith(".. version-deprecated")
-        if msg is None:
-            assert len(lines) == 3 or not lines[3].startswith("   ")
-        else:
-            assert lines[3] == f"   {msg}"
+        assert len(lines[1].strip()) == 0, "expected empty line following summary"
+
+    assert lines[offset].startswith(".. version-deprecated")
+    if msg is None:
+        assert len(lines) == offset + 1 or not lines[offset + 1].startswith("   ")
+    else:
+        msg_lines = msg.splitlines()
+        msg_indented = [f"   {line}" for line in msg_lines]
+        assert lines[offset + 1 : offset + 1 + len(msg_lines)] == msg_indented