diff --git a/numpy/core/tests/test_scalar_methods.py b/numpy/core/tests/test_scalar_methods.py
index 18a7bc8..a51e4f1 100644
--- a/numpy/core/tests/test_scalar_methods.py
+++ b/numpy/core/tests/test_scalar_methods.py
@@ -2,7 +2,6 @@
 Test the scalar constructors, which also do type-coercion
 """
 import fractions
-import platform
 import types
 from typing import Any, Type
 
@@ -10,6 +9,7 @@
 import numpy as np
 
 from numpy.testing import assert_equal, assert_raises, IS_MUSL
+from numpy.testing._private.utils import LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE
 
 
 class TestAsIntegerRatio:
@@ -84,7 +84,7 @@ def test_against_known_values(self):
                     np.finfo(np.double) == np.finfo(np.longdouble),
                     reason="long double is same as double"),
                 pytest.mark.skipif(
-                    platform.machine().startswith("ppc"),
+                    LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE,
                     reason="IBM double double"),
             ]
         )
diff --git a/numpy/core/tests/test_scalarmath.py b/numpy/core/tests/test_scalarmath.py
index 9977c8b..f8e0a29 100644
--- a/numpy/core/tests/test_scalarmath.py
+++ b/numpy/core/tests/test_scalarmath.py
@@ -23,6 +23,8 @@
 except TypeError:
     USING_CLANG_CL = False
 
+from numpy.testing._private.utils import LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE
+
 types = [np.bool_, np.byte, np.ubyte, np.short, np.ushort, np.intc, np.uintc,
          np.int_, np.uint, np.longlong, np.ulonglong,
          np.single, np.double, np.longdouble, np.csingle,
@@ -528,7 +530,7 @@ def test_int_from_infinite_longdouble___int__(self):
 
     @pytest.mark.skipif(np.finfo(np.double) == np.finfo(np.longdouble),
                         reason="long double is same as double")
-    @pytest.mark.skipif(platform.machine().startswith("ppc"),
+    @pytest.mark.skipif(LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE,
                         reason="IBM double double")
     def test_int_from_huge_longdouble(self):
         # Produce a longdouble that would overflow a double,
diff --git a/numpy/core/tests/test_scalarprint.py b/numpy/core/tests/test_scalarprint.py
index 98d1f4a..65cdeb3 100644
--- a/numpy/core/tests/test_scalarprint.py
+++ b/numpy/core/tests/test_scalarprint.py
@@ -2,13 +2,13 @@
 
 """
 import code
-import platform
 import pytest
 import sys
 
 from tempfile import TemporaryFile
 import numpy as np
 from numpy.testing import assert_, assert_equal, assert_raises, IS_MUSL
+from numpy.testing._private.utils import LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE
 
 class TestRealScalars:
     def test_str(self):
@@ -308,8 +308,8 @@ def test_dragon4_interface(self):
             assert_equal(fpos(tp('1.'), trim='-'), "1")
             assert_equal(fpos(tp('1.001'), precision=1, trim='-'), "1")
 
-    @pytest.mark.skipif(not platform.machine().startswith("ppc64"),
-                        reason="only applies to ppc float128 values")
+    @pytest.mark.skipif(not LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE,
+                        reason="only applies to ppc double-double values")
     def test_ppc64_ibm_double_double128(self):
         # check that the precision decreases once we get into the subnormal
         # range. Unlike float64, this starts around 1e-292 instead of 1e-308,
diff --git a/numpy/core/tests/test_umath.py b/numpy/core/tests/test_umath.py
index 963e740..ec59058 100644
--- a/numpy/core/tests/test_umath.py
+++ b/numpy/core/tests/test_umath.py
@@ -20,7 +20,10 @@
     _gen_alignment_data, assert_array_almost_equal_nulp, IS_WASM, IS_MUSL,
     IS_PYPY
     )
-from numpy.testing._private.utils import _glibc_older_than
+from numpy.testing._private.utils import (
+    LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE,
+    _glibc_older_than,
+)
 
 UFUNCS = [obj for obj in np.core.umath.__dict__.values()
          if isinstance(obj, np.ufunc)]
@@ -4452,7 +4455,7 @@ def test_nextafterf():
 
 @pytest.mark.skipif(np.finfo(np.double) == np.finfo(np.longdouble),
                     reason="long double is same as double")
-@pytest.mark.xfail(condition=platform.machine().startswith("ppc64"),
+@pytest.mark.xfail(condition=LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE,
                     reason="IBM double double")
 def test_nextafterl():
     return _test_nextafter(np.longdouble)
@@ -4491,7 +4494,7 @@ def test_spacingf():
 
 @pytest.mark.skipif(np.finfo(np.double) == np.finfo(np.longdouble),
                     reason="long double is same as double")
-@pytest.mark.xfail(condition=platform.machine().startswith("ppc64"),
+@pytest.mark.xfail(condition=LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE,
                     reason="IBM double double")
 def test_spacingl():
     return _test_spacing(np.longdouble)
diff --git a/numpy/testing/_private/utils.py b/numpy/testing/_private/utils.py
index 28dd656..0a842a9 100644
--- a/numpy/testing/_private/utils.py
+++ b/numpy/testing/_private/utils.py
@@ -67,6 +67,9 @@ class KnownFailureException(Exception):
 if 'musl' in _v:
     IS_MUSL = True
 
+LONG_DOUBLE_IS_IBM_DOUBLE_DOUBLE = (platform.machine().startswith("ppc")
+                                    and str(np.finfo(np.longdouble).max)
+                                    == "1.79769313486231580793728971405301e+308")
 
 def assert_(val, msg=''):
     """