diff --git a/src/runtime/panic.c b/src/runtime/panic.c
index 55ad80e..24eb6db 100644
--- a/src/runtime/panic.c
+++ b/src/runtime/panic.c
@@ -34,6 +34,8 @@
 	g->m->scalararg[1] = 0;
 
 	d = runtime·newdefer(siz);
+	if(d->panic != nil)
+		runtime·throw("deferproc: d->panic != nil after newdefer");
 	d->fn = fn;
 	d->pc = callerpc;
 	d->argp = argp;
diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index 7eb2d60..c78102f 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -188,6 +188,10 @@
 // The defer cannot be used after this call.
 //go:nosplit
 func freedefer(d *_defer) {
+	if d._panic != nil {
+		// _panic must be cleared before d is unlinked from gp.
+		gothrow("freedefer with d._panic != nil")
+	}
 	sc := deferclass(uintptr(d.siz))
 	if sc < uintptr(len(p{}.deferpool)) {
 		mp := acquirem()
@@ -258,6 +262,7 @@
 		if d.started {
 			if d._panic != nil {
 				d._panic.aborted = true
+				d._panic = nil
 			}
 			gp._defer = d.link
 			freedefer(d)
@@ -268,6 +273,7 @@
 		if gp._defer != d {
 			gothrow("bad defer entry in Goexit")
 		}
+		d._panic = nil
 		gp._defer = d.link
 		freedefer(d)
 		// Note: we ignore recovers here because Goexit isn't a panic
@@ -343,6 +349,7 @@
 			if d._panic != nil {
 				d._panic.aborted = true
 			}
+			d._panic = nil
 			gp._defer = d.link
 			freedefer(d)
 			continue
@@ -366,6 +373,7 @@
 		if gp._defer != d {
 			gothrow("bad defer entry in panic")
 		}
+		d._panic = nil
 		gp._defer = d.link
 
 		// trigger shrinkage to test stack copy.  See stack_test.go:TestStackPanic