diff --git a/Lib/test/test_array.py b/Lib/test/test_array.py
index d9b608fb23d0c6..c931be6df5fdaa 100755
--- a/Lib/test/test_array.py
+++ b/Lib/test/test_array.py
@@ -1583,6 +1583,22 @@ def test_byteswap(self):
             b.byteswap()
             self.assertEqual(a, b)
 
+    def test_byteswap_single_call_result(self):
+        # A single byteswap() must swap each item's two halves (real,
+        # imag) independently. test_byteswap above only checks that
+        # byteswap() twice round-trips to the original, which passes
+        # even if a single call scrambles multi-item arrays.
+        a = array.array(self.typecode, self.example)
+        original = a.tobytes()
+        a.byteswap()
+        itemsize = a.itemsize
+        half = itemsize // 2
+        expected = bytearray()
+        for i in range(0, len(original), itemsize):
+            item = original[i:i + itemsize]
+            expected += item[half - 1::-1] + item[itemsize - 1:half - 1:-1]
+        self.assertEqual(a.tobytes(), bytes(expected))
+
 
 class HalfFloatTest(FPTest, unittest.TestCase):
     example = [-42.0, 0, 42, 1e2, -1e4]
diff --git a/Lib/test/test_import/__init__.py b/Lib/test/test_import/__init__.py
index 9f6dec7d1c5802..7e92028cb955cb 100644
--- a/Lib/test/test_import/__init__.py
+++ b/Lib/test/test_import/__init__.py
@@ -490,6 +490,7 @@ def test_with_extension(ext):
                 forget(TESTFN)
                 unlink(source)
                 unlink(pyc)
+                rmtree('__pycache__')
 
         sys.path.insert(0, os.curdir)
         try:
@@ -668,6 +669,7 @@ def __del__(self):
                   import importlib
             sys.argv.insert(0, C())
             """))
+        self.addCleanup(unlink, testfn)
         script_helper.assert_python_ok(testfn)
 
     @skip_if_dont_write_bytecode
@@ -2033,6 +2035,7 @@ def test_unencodable_filename(self):
         # encode filenames, especially on Windows
         pyname = script_helper.make_script('', TESTFN_UNENCODABLE, 'pass')
         self.addCleanup(unlink, pyname)
+        self.addCleanup(rmtree, '__pycache__')
         name = pyname[:-3]
         script_helper.assert_python_ok("-c", "mod = __import__(%a)" % name,
                                        __isolated=False)
diff --git a/Lib/test/test_math.py b/Lib/test/test_math.py
index cc37697189af3e..a27996dd01c9d1 100644
--- a/Lib/test/test_math.py
+++ b/Lib/test/test_math.py
@@ -2682,11 +2682,8 @@ def test_fma_infinities(self):
     @unittest.skipIf(
         sys.platform.startswith(("freebsd", "wasi", "netbsd", "emscripten", "cygwin"))
         or (sys.platform == "android" and platform.machine() == "x86_64")
-        or support.linked_to_musl(),  # gh-131032
+        or (support.linked_to_musl() and support.linked_to_musl() < (1, 2, 6)),  # gh-131032
         f"this platform doesn't implement IEE 754-2008 properly")
-    # gh-131032: musl is fixed but the fix is not yet released; when the fixed
-    # version is known change this to:
-    #   or support.linked_to_musl() < (1, <m>, <p>)
     def test_fma_zero_result(self):
         nonnegative_finites = [0.0, 1e-300, 2.3, 1e300]
 
diff --git a/Misc/NEWS.d/next/Library/2026-07-23-20-00-00.gh-issue-154566.byteswap-zd.rst b/Misc/NEWS.d/next/Library/2026-07-23-20-00-00.gh-issue-154566.byteswap-zd.rst
new file mode 100644
index 00000000000000..e86b9a979946cd
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-07-23-20-00-00.gh-issue-154566.byteswap-zd.rst
@@ -0,0 +1,4 @@
+Fix :meth:`array.array.byteswap` corrupting data for ``'Zd'`` (complex
+double) arrays with more than one element: the 16-byte item loop advanced
+the buffer pointer by only 8 bytes per iteration, causing items after the
+first to be scrambled.
diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 39a399d7a49cf5..a0181c083a6036 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -1617,7 +1617,7 @@ array_array_byteswap_impl(arrayobject *self)
         break;
     case 16:
         assert(strcmp(self->ob_descr->typecode, "Zd") == 0);
-        for (p = self->ob_item, i = Py_SIZE(self); --i >= 0; p += 8) {
+        for (p = self->ob_item, i = Py_SIZE(self); --i >= 0; p += 16) {
             char t0 = p[0];
             char t1 = p[1];
             char t2 = p[2];