diff --git a/src/runtime/os3_plan9.go b/src/runtime/os3_plan9.go
index 27519debd35..fa49ad681f3 100644
--- a/src/runtime/os3_plan9.go
+++ b/src/runtime/os3_plan9.go
@@ -6,6 +6,8 @@ package runtime
 
 import "unsafe"
 
+// May run during STW, so write barriers are not allowed.
+//go:nowritebarrier
 func sighandler(_ureg *ureg, note *byte, gp *g) int {
 	_g_ := getg()
 	var t sigTabT
@@ -79,7 +81,7 @@ func sighandler(_ureg *ureg, note *byte, gp *g) int {
 	}
 Throw:
 	_g_.m.throwing = 1
-	_g_.m.caughtsig = gp
+	setGNoWriteBarrier(&_g_.m.caughtsig, gp)
 	startpanic()
 	print(notestr, "\n")
 	print("PC=", hex(c.pc()), "\n")
diff --git a/src/runtime/signal_386.go b/src/runtime/signal_386.go
index 0ca593de029..b63299511f6 100644
--- a/src/runtime/signal_386.go
+++ b/src/runtime/signal_386.go
@@ -24,6 +24,8 @@ func dumpregs(c *sigctxt) {
 	print("gs     ", hex(c.gs()), "\n")
 }
 
+// May run during STW, so write barriers are not allowed.
+//go:nowritebarrier
 func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	_g_ := getg()
 	c := &sigctxt{info, ctxt}
@@ -98,7 +100,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	}
 
 	_g_.m.throwing = 1
-	_g_.m.caughtsig = gp
+	setGNoWriteBarrier(&_g_.m.caughtsig, gp)
 	startpanic()
 
 	if sig < uint32(len(sigtable)) {
diff --git a/src/runtime/signal_amd64x.go b/src/runtime/signal_amd64x.go
index cd87d76a50a..5dc9d8070a8 100644
--- a/src/runtime/signal_amd64x.go
+++ b/src/runtime/signal_amd64x.go
@@ -37,6 +37,8 @@ func dumpregs(c *sigctxt) {
 
 var crashing int32
 
+// May run during STW, so write barriers are not allowed.
+//go:nowritebarrier
 func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	_g_ := getg()
 	c := &sigctxt{info, ctxt}
@@ -134,7 +136,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	}
 
 	_g_.m.throwing = 1
-	_g_.m.caughtsig = gp
+	setGNoWriteBarrier(&_g_.m.caughtsig, gp)
 
 	if crashing == 0 {
 		startpanic()
diff --git a/src/runtime/signal_arm.go b/src/runtime/signal_arm.go
index c07b45ef18c..7d417fa2b3c 100644
--- a/src/runtime/signal_arm.go
+++ b/src/runtime/signal_arm.go
@@ -32,6 +32,8 @@ func dumpregs(c *sigctxt) {
 	print("fault   ", hex(c.fault()), "\n")
 }
 
+// May run during STW, so write barriers are not allowed.
+//go:nowritebarrier
 func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	_g_ := getg()
 	c := &sigctxt{info, ctxt}
@@ -93,7 +95,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	}
 
 	_g_.m.throwing = 1
-	_g_.m.caughtsig = gp
+	setGNoWriteBarrier(&_g_.m.caughtsig, gp)
 	startpanic()
 
 	if sig < uint32(len(sigtable)) {
diff --git a/src/runtime/signal_arm64.go b/src/runtime/signal_arm64.go
index cc8985872ca..efb84029e28 100644
--- a/src/runtime/signal_arm64.go
+++ b/src/runtime/signal_arm64.go
@@ -45,6 +45,8 @@ func dumpregs(c *sigctxt) {
 	print("fault   ", hex(c.fault()), "\n")
 }
 
+// May run during STW, so write barriers are not allowed.
+//go:nowritebarrier
 func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	_g_ := getg()
 	c := &sigctxt{info, ctxt}
@@ -106,7 +108,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	}
 
 	_g_.m.throwing = 1
-	_g_.m.caughtsig = gp
+	setGNoWriteBarrier(&_g_.m.caughtsig, gp)
 	startpanic()
 
 	if sig < uint32(len(sigtable)) {
diff --git a/src/runtime/signal_ppc64x.go b/src/runtime/signal_ppc64x.go
index 94b4708dd59..018d7d62efa 100644
--- a/src/runtime/signal_ppc64x.go
+++ b/src/runtime/signal_ppc64x.go
@@ -50,6 +50,8 @@ func dumpregs(c *sigctxt) {
 	print("trap ", hex(c.trap()), "\n")
 }
 
+// May run during STW, so write barriers are not allowed.
+//go:nowritebarrier
 func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	_g_ := getg()
 	c := &sigctxt{info, ctxt}
@@ -111,7 +113,7 @@ func sighandler(sig uint32, info *siginfo, ctxt unsafe.Pointer, gp *g) {
 	}
 
 	_g_.m.throwing = 1
-	_g_.m.caughtsig = gp
+	setGNoWriteBarrier(&_g_.m.caughtsig, gp)
 	startpanic()
 
 	if sig < uint32(len(sigtable)) {