diff --git a/Tests/test_file_libtiff.py b/Tests/test_file_libtiff.py
index 6c32b5ad427..0c21c9fab66 100644
--- a/Tests/test_file_libtiff.py
+++ b/Tests/test_file_libtiff.py
@@ -281,11 +281,7 @@ class Tc(NamedTuple):
             )
         }
 
-        libtiffs = [False]
-        if Image.core.libtiff_support_custom_tags:
-            libtiffs.append(True)
-
-        for libtiff in libtiffs:
+        for libtiff in [False, True]:
             TiffImagePlugin.WRITE_LIBTIFF = libtiff
 
             def check_tags(
@@ -691,8 +687,7 @@ def test_exif_ifd(self, tmp_path: Path) -> None:
             im.save(outfile)
 
         with Image.open(outfile) as reloaded:
-            if Image.core.libtiff_support_custom_tags:
-                assert reloaded.tag_v2[34665] == 125456
+            assert reloaded.tag_v2[34665] == 125456
 
     def test_crashing_metadata(self, tmp_path: Path) -> None:
         # issue 1597
@@ -756,12 +751,7 @@ def check_write(libtiff: bool) -> None:
             with Image.open(out) as reloaded:
                 assert icc_profile == reloaded.info["icc_profile"]
 
-        libtiffs = []
-        if Image.core.libtiff_support_custom_tags:
-            libtiffs.append(True)
-        libtiffs.append(False)
-
-        for libtiff in libtiffs:
+        for libtiff in [True, False]:
             check_write(libtiff)
 
     def test_multipage_compression(self) -> None:
diff --git a/src/PIL/TiffImagePlugin.py b/src/PIL/TiffImagePlugin.py
index 10ac9ea3a2a..44103f37669 100644
--- a/src/PIL/TiffImagePlugin.py
+++ b/src/PIL/TiffImagePlugin.py
@@ -1823,9 +1823,6 @@ def _save(im, fp, filename):
             # Custom items are supported for int, float, unicode, string and byte
             # values. Other types and tuples require a tagtype.
             if tag not in TiffTags.LIBTIFF_CORE:
-                if not getattr(Image.core, "libtiff_support_custom_tags", False):
-                    continue
-
                 if tag in ifd.tagtype:
                     types[tag] = ifd.tagtype[tag]
                 elif not (isinstance(value, (int, float, str, bytes))):
diff --git a/src/_imaging.c b/src/_imaging.c
index 520e5079346..8d9c2d257b3 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -4388,16 +4388,6 @@ setup_module(PyObject *m) {
         PyObject *v = PyUnicode_FromString(ImagingTiffVersion());
         PyDict_SetItemString(d, "libtiff_version", v ? v : Py_None);
         Py_XDECREF(v);
-
-        // Test for libtiff 4.0 or later, excluding libtiff 3.9.6 and 3.9.7
-        PyObject *support_custom_tags;
-#if TIFFLIB_VERSION >= 20111221 && TIFFLIB_VERSION != 20120218 && \
-    TIFFLIB_VERSION != 20120922
-        support_custom_tags = Py_True;
-#else
-        support_custom_tags = Py_False;
-#endif
-        PyDict_SetItemString(d, "libtiff_support_custom_tags", support_custom_tags);
     }
 #endif