diff -up ./config.m4.noatfork ./config.m4
--- ./config.m4.noatfork	2022-01-31 14:03:14.032856870 +0100
+++ ./config.m4	2022-01-31 14:07:39.424150191 +0100
@@ -1102,7 +1102,6 @@ if test "$PHP_GRPC" != "no"; then
     , $ext_shared, , -fvisibility=hidden \
     -DOPENSSL_NO_ASM -D_GNU_SOURCE -DWIN32_LEAN_AND_MEAN \
     -D_HAS_EXCEPTIONS=0 -DNOMINMAX -DGRPC_ARES=0 \
-    -DGRPC_POSIX_FORK_ALLOW_PTHREAD_ATFORK=1 \
     -DGRPC_XDS_USER_AGENT_NAME_SUFFIX='"\"PHP\""' \
     -DGRPC_XDS_USER_AGENT_VERSION_SUFFIX='"\"1.45.0\""')