diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index a7a3fb6..538ed0a 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -775,6 +775,7 @@
 	}
 
 	sched.maxmcount = 10000
+	crashFD.Store(^uintptr(0))
 
 	// The world starts stopped.
 	worldStopped()
diff --git a/src/runtime/runtime.go b/src/runtime/runtime.go
index 4dfb2f8..c7a511b 100644
--- a/src/runtime/runtime.go
+++ b/src/runtime/runtime.go
@@ -244,6 +244,8 @@
 // set by debug.SetCrashOutput (see #42888). If it is a valid fd (not
 // all ones), writeErr and related functions write to it in addition
 // to standard error.
+//
+// Initialized to -1 in schedinit.
 var crashFD atomic.Uintptr
 
 //go:linkname setCrashFD