diff --git a/pkg/sentry/platform/systrap/stub_unsafe.go b/pkg/sentry/platform/systrap/stub_unsafe.go
index 25a119aa7..462e66923 100644
--- a/pkg/sentry/platform/systrap/stub_unsafe.go
+++ b/pkg/sentry/platform/systrap/stub_unsafe.go
@@ -149,7 +149,7 @@ func stubInit() {
 	// Allocate maxGuestThreads plus ONE because each per-thread stack
 	// has to be aligned to sysmsg.PerThreadMemSize.
 	// Look at sysmsg/sighandler.c:sysmsg_addr() for more details.
-	mapLen, _ = hostarch.PageRoundUp(mapLen + sysmsg.PerThreadMemSize*(maxSystemThreads+1))
+	mapLen, _ = hostarch.PageRoundUp(mapLen + sysmsg.PerThreadMemSize*(uintptr(maxChildThreads+1)))
 
 	// Allocate context queue region
 	stubContextQueueRegion = mapLen
diff --git a/pkg/sentry/platform/systrap/subprocess.go b/pkg/sentry/platform/systrap/subprocess.go
index d978c69f1..d3ef17d76 100644
--- a/pkg/sentry/platform/systrap/subprocess.go
+++ b/pkg/sentry/platform/systrap/subprocess.go
@@ -101,15 +101,16 @@ type requestStub struct {
 	done chan *thread
 }
 
-// maxSysmsgThreads specifies the maximum number of system threads that a
-// subprocess can create in context decoupled mode.
-// TODO(b/268366549): Replace maxSystemThreads below.
-var maxSysmsgThreads = runtime.GOMAXPROCS(0)
+// maxSysmsgThreads is the maximum number of sysmsg threads that a subprocess
+// can create. It is based on GOMAXPROCS and set once, so it must be set after
+// GOMAXPROCS has been adjusted (see loader.go:Args.NumCPU).
+var maxSysmsgThreads = 0
+
+// maxChildThreads is the max number of all child system threads that a
+// subprocess can create, including sysmsg threads.
+var maxChildThreads = 0
 
 const (
-	// maxSystemThreads specifies the maximum number of system threads that a
-	// subprocess may create in order to process the contexts.
-	maxSystemThreads = 4096
 	// maxGuestContexts specifies the maximum number of task contexts that a
 	// subprocess can handle.
 	maxGuestContexts = 4095
@@ -318,7 +319,7 @@ func newSubprocess(create func() (*thread, error), memoryFile *pgalloc.MemoryFil
 	sp := &subprocess{
 		requests:          requests,
 		faultedContexts:   make(map[*platformContext]struct{}),
-		sysmsgStackPool:   pool.Pool{Start: 0, Limit: maxSystemThreads},
+		sysmsgStackPool:   pool.Pool{Start: 0, Limit: uint64(maxChildThreads)},
 		threadContextPool: pool.Pool{Start: 0, Limit: maxGuestContexts},
 		memoryFile:        memoryFile,
 		sysmsgThreads:     make(map[uint32]*sysmsgThread),
diff --git a/pkg/sentry/platform/systrap/systrap.go b/pkg/sentry/platform/systrap/systrap.go
index 7a5310f7a..5527c09b7 100644
--- a/pkg/sentry/platform/systrap/systrap.go
+++ b/pkg/sentry/platform/systrap/systrap.go
@@ -318,6 +318,10 @@ func (*Systrap) MinUserAddress() hostarch.Addr {
 func New() (*Systrap, error) {
 	// CPUID information has been initialized at this point.
 	archState.Init()
+	// GOMAXPROCS has been set at this point.
+	maxSysmsgThreads = runtime.GOMAXPROCS(0)
+	// Account for syscall thread.
+	maxChildThreads = maxSysmsgThreads + 1
 
 	mf, err := createMemoryFile()
 	if err != nil {