diff --git a/src/_pytest/_code/source.py b/src/_pytest/_code/source.py
index 1c69498ea..0bc2e243e 100644
--- a/src/_pytest/_code/source.py
+++ b/src/_pytest/_code/source.py
@@ -25,13 +25,14 @@ if TYPE_CHECKING:
 
 
 class Source:
-    """ an immutable object holding a source code fragment,
-        possibly deindenting it.
+    """An immutable object holding a source code fragment.
+
+    When using Source(...), the source lines are deindented.
     """
 
     _compilecounter = 0
 
-    def __init__(self, *parts, deindent: bool = True) -> None:
+    def __init__(self, *parts) -> None:
         self.lines = lines = []  # type: List[str]
         for part in parts:
             if not part:
@@ -43,9 +44,8 @@ class Source:
             elif isinstance(part, str):
                 partlines = part.split("\n")
             else:
-                partlines = getsource(part, deindent=deindent).lines
-            if deindent:
-                partlines = _deindent_function(partlines)
+                partlines = getsource(part).lines
+            partlines = deindent(partlines)
             lines.extend(partlines)
 
     def __eq__(self, other):
@@ -306,24 +306,20 @@ def getrawcode(obj, trycall: bool = True):
         return obj
 
 
-def getsource(obj, *, deindent: bool = True) -> Source:
+def getsource(obj) -> Source:
     obj = getrawcode(obj)
     try:
         strsrc = inspect.getsource(obj)
     except IndentationError:
         strsrc = '"Buggy python version consider upgrading, cannot get source"'
     assert isinstance(strsrc, str)
-    return Source(strsrc, deindent=deindent)
+    return Source(strsrc)
 
 
 def deindent(lines: Sequence[str]) -> List[str]:
     return textwrap.dedent("\n".join(lines)).splitlines()
 
 
-# Internal alias to avoid shadowing with `deindent` parameter.
-_deindent_function = deindent
-
-
 def get_statement_startend2(lineno: int, node: ast.AST) -> Tuple[int, Optional[int]]:
     # flatten all statements and except handlers into one lineno-list
     # AST's line numbers start indexing at 1
diff --git a/testing/code/test_source.py b/testing/code/test_source.py
index 35728c334..014034dec 100644
--- a/testing/code/test_source.py
+++ b/testing/code/test_source.py
@@ -4,6 +4,7 @@
 import ast
 import inspect
 import sys
+import textwrap
 from types import CodeType
 from typing import Any
 from typing import Dict
@@ -64,8 +65,6 @@ def test_source_from_inner_function() -> None:
     def f():
         pass
 
-    source = _pytest._code.Source(f, deindent=False)
-    assert str(source).startswith("    def f():")
     source = _pytest._code.Source(f)
     assert str(source).startswith("def f():")
 
@@ -557,7 +556,7 @@ def test_code_of_object_instance_with_call() -> None:
 def getstatement(lineno: int, source) -> Source:
     from _pytest._code.source import getstatementrange_ast
 
-    src = _pytest._code.Source(source, deindent=False)
+    src = _pytest._code.Source(source)
     ast, start, end = getstatementrange_ast(lineno, src)
     return src[start:end]
 
@@ -633,7 +632,7 @@ def test_source_with_decorator() -> None:
         assert False
 
     src = inspect.getsource(deco_mark)
-    assert str(Source(deco_mark, deindent=False)) == src
+    assert textwrap.indent(str(Source(deco_mark)), "    ") + "\n" == src
     assert src.startswith("    @pytest.mark.foo")
 
     @pytest.fixture
@@ -646,7 +645,9 @@ def test_source_with_decorator() -> None:
     # existing behavior here for explicitness, but perhaps we should revisit/change this
     # in the future
     assert str(Source(deco_fixture)).startswith("@functools.wraps(function)")
-    assert str(Source(get_real_func(deco_fixture), deindent=False)) == src
+    assert (
+        textwrap.indent(str(Source(get_real_func(deco_fixture))), "    ") + "\n" == src
+    )
 
 
 def test_single_line_else() -> None: