diff --git a/codex-cli/src/utils/agent/sandbox/macos-seatbelt.ts b/codex-cli/src/utils/agent/sandbox/macos-seatbelt.ts
index 290e6b56..162fe908 100644
--- a/codex-cli/src/utils/agent/sandbox/macos-seatbelt.ts
+++ b/codex-cli/src/utils/agent/sandbox/macos-seatbelt.ts
@@ -147,4 +147,8 @@ const READ_ONLY_SEATBELT_POLICY = `
   (sysctl-name "kern.version")
   (sysctl-name "sysctl.proc_cputype")
   (sysctl-name-prefix "hw.perflevel")
-)`.trim();
+)
+
+; Added on top of Chrome profile
+; Needed for python multiprocessing on MacOS for the SemLock
+(allow ipc-posix-sem)`.trim();
diff --git a/codex-rs/core/src/seatbelt_base_policy.sbpl b/codex-rs/core/src/seatbelt_base_policy.sbpl
index c9664651..b2504948 100644
--- a/codex-rs/core/src/seatbelt_base_policy.sbpl
+++ b/codex-rs/core/src/seatbelt_base_policy.sbpl
@@ -65,3 +65,7 @@
   (sysctl-name "sysctl.proc_cputype")
   (sysctl-name-prefix "hw.perflevel")
 )
+
+; Added on top of Chrome profile
+; Needed for python multiprocessing on MacOS for the SemLock
+(allow ipc-posix-sem)