diff --git a/.github/workflows/reusable-wasi.yml b/.github/workflows/reusable-wasi.yml
index a309ef4e7f4485..91d76fd1b5f8c5 100644
--- a/.github/workflows/reusable-wasi.yml
+++ b/.github/workflows/reusable-wasi.yml
@@ -13,7 +13,7 @@ jobs:
     timeout-minutes: 60
     env:
       WASMTIME_VERSION: 38.0.3
-      WASI_SDK_VERSION: 25
+      WASI_SDK_VERSION: 29
       WASI_SDK_PATH: /opt/wasi-sdk
       CROSS_BUILD_PYTHON: cross-build/build
       CROSS_BUILD_WASI: cross-build/wasm32-wasip1
diff --git a/Include/pyport.h b/Include/pyport.h
index b250f9e308f2dd..97c0e195d19808 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -504,6 +504,7 @@ extern "C" {
  * Thread support is stubbed and any attempt to create a new thread fails.
  */
 #if (!defined(HAVE_PTHREAD_STUBS) && \
+     !defined(__wasi__) && \
       (!defined(__EMSCRIPTEN__) || defined(__EMSCRIPTEN_PTHREADS__)))
 #  define Py_CAN_START_THREADS 1
 #endif
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 2f169c1165df05..2e87e38fe5dfdc 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -730,14 +730,12 @@ def test_thread_info(self):
         self.assertEqual(len(info), 3)
         self.assertIn(info.name, ('nt', 'pthread', 'pthread-stubs', 'solaris', None))
         self.assertIn(info.lock, ('pymutex', None))
-        if sys.platform.startswith(("linux", "android", "freebsd")):
+        if sys.platform.startswith(("linux", "android", "freebsd", "wasi")):
             self.assertEqual(info.name, "pthread")
         elif sys.platform == "win32":
             self.assertEqual(info.name, "nt")
         elif sys.platform == "emscripten":
             self.assertIn(info.name, {"pthread", "pthread-stubs"})
-        elif sys.platform == "wasi":
-            self.assertEqual(info.name, "pthread-stubs")
 
     def test_abi_info(self):
         info = sys.abi_info
diff --git a/Misc/NEWS.d/next/Build/2025-11-19-09-21-17.gh-issue-141172.cYWc4x.rst b/Misc/NEWS.d/next/Build/2025-11-19-09-21-17.gh-issue-141172.cYWc4x.rst
new file mode 100644
index 00000000000000..7cade1ebd414e3
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2025-11-19-09-21-17.gh-issue-141172.cYWc4x.rst
@@ -0,0 +1 @@
+Update to WASI SDK 29.
diff --git a/Tools/wasm/wasi/__main__.py b/Tools/wasm/wasi/__main__.py
index bb5ce30c5d8b4f..59ffd436258185 100644
--- a/Tools/wasm/wasi/__main__.py
+++ b/Tools/wasm/wasi/__main__.py
@@ -31,7 +31,7 @@
     b"# Required to statically build extension modules."
 )
 
-WASI_SDK_VERSION = 25
+WASI_SDK_VERSION = 29
 
 WASMTIME_VAR_NAME = "WASMTIME"
 WASMTIME_HOST_RUNNER_VAR = f"{{{WASMTIME_VAR_NAME}}}"
@@ -419,8 +419,8 @@ def main():
         f"{WASMTIME_HOST_RUNNER_VAR} run "
         # Make sure the stack size will work for a pydebug
         # build.
-        # Use 16 MiB stack.
-        "--wasm max-wasm-stack=16777216 "
+        # Use 32 MiB stack.
+        "--wasm max-wasm-stack=33554432 "
         # Enable thread support; causes use of preview1.
         # "--wasm threads=y --wasi threads=y "
         # Map the checkout to / to load the stdlib from /Lib.