diff --git a/scripts/build_gc_release_android.bat b/scripts/build_gc_release_android.bat
index db9ce3621..5b5cf3247 100644
--- a/scripts/build_gc_release_android.bat
+++ b/scripts/build_gc_release_android.bat
@@ -5,6 +5,11 @@
 @rem Needs the Android NDK (tested with r30) in ANDROID_NDK_HOME, and Ninja. Installs into
 @rem 3rdParty\gc\android\<abi>\release. API level 29 is the floor the default library needs
 @rem (timespec_get).
+@rem
+@rem Parallel marking is off: with it, several threads allocating at once deadlocked the
+@rem collector during marking on an API 29 x86_64 emulator (bdwgc 8.2.12 and master; reported
+@rem upstream as https://github.com/bdwgc/bdwgc/issues/980). Marking then runs on the collecting
+@rem thread alone.
 @echo off
 setlocal
 
@@ -32,6 +37,6 @@ cmake -S "%ROOT%\3rdParty\gc-8.2.12" -B "%BUILD_DIR%" -G Ninja -Wno-dev ^
     -DANDROID_ABI=%ABI% -DANDROID_PLATFORM=android-29 ^
     -DCMAKE_BUILD_TYPE=Release -DBUILD_SHARED_LIBS=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON ^
     -DCMAKE_INSTALL_PREFIX="%ROOT%\3rdParty\gc\android\%ABI%\release" ^
-    -Denable_threads=ON -Denable_cplusplus=OFF -Denable_docs=OFF -Dbuild_tests=OFF -Dbuild_cord=OFF || exit /b 1
+    -Denable_threads=ON -Denable_parallel_mark=OFF -Denable_cplusplus=OFF -Denable_docs=OFF -Dbuild_tests=OFF -Dbuild_cord=OFF || exit /b 1
 cmake --build "%BUILD_DIR%" -j 8 || exit /b 1
 cmake --install "%BUILD_DIR%" || exit /b 1