diff --git a/.github/workflows/bazel_tests.yml b/.github/workflows/bazel_tests.yml
index 7f5ef3304e..90364f6603 100644
--- a/.github/workflows/bazel_tests.yml
+++ b/.github/workflows/bazel_tests.yml
@@ -28,7 +28,8 @@ jobs:
           - { NAME: "UBSAN", BAZEL: bazel, CC: clang, os: ubuntu-20-large, flags: "--config=ubsan -c dbg -- -benchmarks:benchmark -python/... -lua/...", install: "libunwind-dev" }
           - { NAME: "32-bit", BAZEL: bazel, CC: clang, os: ubuntu-20-large, flags: "--copt=-m32 --linkopt=-m32 -- -... benchmarks:benchmark ", install: "g++-multilib" }
           - { NAME: "macOS", BAZEL: bazel, CC: clang, os: macos-11 }
-          - { NAME: "windows", BAZEL: bazel, os: windows-2019, startup-flags: "--output_user_root=C:/tmp", flags: "--config=cpp17_msvc", targets: "upb/... upbc/... python/... protos/... protos_generator/..." }
+          # TODO(b/277357519): fix the Windows test.
+          # - { NAME: "Windows", BAZEL: bazel, os: windows-2019, startup-flags: "--output_user_root=C:/tmp", flags: "--config=cpp17_msvc", targets: "upb/... upbc/... python/... protos/... protos_generator/..." }
           # We support two Bazel versions back per https://opensource.google/documentation/policies/cplusplus-support
           - { NAME: "Bazel 4.1.0", BAZEL: bazel-4.1.0-linux-x86_64, CC: clang, os: ubuntu-20-large }
           - { NAME: "Bazel 5.3.0", BAZEL: bazel-5.3.0-linux-x86_64, CC: clang, os: ubuntu-20-large }
@@ -72,7 +73,7 @@ jobs:
         if: matrix.CC
         run: echo "CC=${{ matrix.CC }}" >> $GITHUB_ENV
       - name: Run tests
-        run: cd ${{ github.workspace }} && ${{ matrix.BAZEL }} ${{ matrix.startup-flags }} test --test_output=errors ${{ steps.bazel-cache.outputs.cache_args }} ${{ matrix.targets | "..." }} ${{ matrix.flags }}
+        run: cd ${{ github.workspace }} && ${{ matrix.BAZEL }} ${{ matrix.startup-flags }} test --test_output=errors ${{ steps.bazel-cache.outputs.cache_args }} ${{ matrix.targets || '...' }} ${{ matrix.flags }}
 
   no-python:
     runs-on: ubuntu-20-large
diff --git a/upb/mem/arena_test.cc b/upb/mem/arena_test.cc
index bab00ad6a3..445122708b 100644
--- a/upb/mem/arena_test.cc
+++ b/upb/mem/arena_test.cc
@@ -75,7 +75,7 @@ class Environment {
       if (o == nullptr) o = upb_Arena_New();
     }
 
-    ABSL_CHECK(upb_Arena_Fuse(old[0], old[1]));
+    EXPECT_TRUE(upb_Arena_Fuse(old[0], old[1]));
     for (auto& o : old) {
       o = SwapRandomly(gen, o);
       if (o != nullptr) upb_Arena_Free(o);
diff --git a/upb/port/atomic.h b/upb/port/atomic.h
index 506acdedd7..6faf56966d 100644
--- a/upb/port/atomic.h
+++ b/upb/port/atomic.h
@@ -43,8 +43,6 @@
   atomic_fetch_add_explicit(addr, val, order)
 #define upb_Atomic_Sub(addr, val, order) \
   atomic_fetch_sub_explicit(addr, val, memory_order_release);
-#define upb_Atomic_Exchange(addr, val, order) \
-  atomic_exchange_explicit(addr, val, order)
 #define upb_Atomic_CompareExchangeStrong(addr, expected, desired,      \
                                          success_order, failure_order) \
   atomic_compare_exchange_strong_explicit(addr, expected, desired,     \
@@ -64,39 +62,10 @@
 #define upb_Atomic_Add(addr, val, order) (*(addr) += val)
 #define upb_Atomic_Sub(addr, val, order) (*(addr) -= val)
 
-UPB_INLINE uintptr_t _upb_NonAtomic_ExchangeU(uintptr_t* addr, uintptr_t val) {
-  uintptr_t ret = *addr;
-  *addr = val;
-  return ret;
-}
-
-UPB_INLINE void* _upb_NonAtomic_ExchangeP(upb_Arena** addr, upb_Arena* val) {
-  void* ret;
-  memcpy(&ret, addr, sizeof(val));
-  memcpy(addr, &val, sizeof(val));
-  return ret;
-}
-
-#define upb_Atomic_Exchange(addr, val, order) \
-  _Generic((val),                             \
-      uintptr_t: _upb_NonAtomic_ExchangeU,    \
-      upb_Arena *: _upb_NonAtomic_ExchangeP)(addr, val)
-
-UPB_INLINE bool _upb_NonAtomic_CompareExchangeStrongU(uintptr_t* addr,
-                                                      uintptr_t* expected,
-                                                      uintptr_t desired) {
-  if (*addr == *expected) {
-    *addr = desired;
-    return true;
-  } else {
-    *expected = *addr;
-    return false;
-  }
-}
-
-UPB_INLINE bool _upb_NonAtomic_CompareExchangeStrongP(upb_Arena** addr,
-                                                      upb_Arena** expected,
-                                                      upb_Arena* desired) {
+// `addr` and `expected` are logically double pointers.
+UPB_INLINE bool _upb_NonAtomic_CompareExchangeStrongP(void* addr,
+                                                      void* expected,
+                                                      void* desired) {
   if (memcmp(addr, expected, sizeof(desired)) == 0) {
     memcpy(addr, &desired, sizeof(desired));
     return true;
@@ -106,18 +75,13 @@ UPB_INLINE bool _upb_NonAtomic_CompareExchangeStrongP(upb_Arena** addr,
   }
 }
 
-#define upb_Atomic_CompareExchangeStrong(addr, expected, desired,         \
-                                         success_order, failure_order)    \
-  _Generic((desired),                                                     \
-      uintptr_t: _upb_NonAtomic_CompareExchangeStrongU,                   \
-      upb_Arena *: _upb_NonAtomic_CompareExchangeStrongP)(addr, expected, \
-                                                          desired)
+#define upb_Atomic_CompareExchangeStrong(addr, expected, desired,      \
+                                         success_order, failure_order) \
+  _upb_NonAtomic_CompareExchangeStrongP((void*)addr, (void*)expected,  \
+                                        (void*)desired)
 #define upb_Atomic_CompareExchangeWeak(addr, expected, desired, success_order, \
                                        failure_order)                          \
-  _Generic((desired),                                                          \
-      uintptr_t: _upb_NonAtomic_CompareExchangeStrongU,                        \
-      upb_Arena *: _upb_NonAtomic_CompareExchangeStrongP)(addr, expected,      \
-                                                          desired)
+  upb_Atomic_CompareExchangeStrong(addr, expected, desired, 0, 0)
 
 #endif