diff --git a/changes/bug11477 b/changes/bug11477
new file mode 100644
index 0000000000000000000000000000000000000000..21dd345912aba31da71ca61c18b1de98c7e71681
--- /dev/null
+++ b/changes/bug11477
@@ -0,0 +1,4 @@
+  o Minor bugfixes (linux syscall sandbox):
+    - Prevent the sandbox from crashing on startup when run with the
+      --enable-expensive-hardening configuration option. Fixes bug
+      11477; bugfix on 0.2.5.4-alpha.
diff --git a/src/common/sandbox.c b/src/common/sandbox.c
index 5c7d8c87bcfe1620ea74af42d698e8e6f7fe6528..bb2b3ed7427694d4d541c7d75bd24e8c325efdbf 100644
--- a/src/common/sandbox.c
+++ b/src/common/sandbox.c
@@ -115,6 +115,7 @@ static int filter_nopar_gen[] = {
 #endif
     SCMP_SYS(getrlimit),
     SCMP_SYS(gettimeofday),
+    SCMP_SYS(gettid),
     SCMP_SYS(getuid),
 #ifdef __NR_getuid32
     SCMP_SYS(getuid32),
@@ -129,6 +130,7 @@ static int filter_nopar_gen[] = {
     SCMP_SYS(munmap),
     SCMP_SYS(read),
     SCMP_SYS(rt_sigreturn),
+    SCMP_SYS(sched_getaffinity),
     SCMP_SYS(set_robust_list),
 #ifdef __NR_sigreturn
     SCMP_SYS(sigreturn),