diff --git a/src/runtime/mheap.go b/src/runtime/mheap.go
index 12307594f05..00d445c1fa9 100644
--- a/src/runtime/mheap.go
+++ b/src/runtime/mheap.go
@@ -363,19 +363,19 @@ var mSpanStateNames = []string{
 	"mSpanFree",
 }
 
-// mSpanStateBox holds an mSpanState and provides atomic operations on
-// it. This is a separate type to disallow accidental comparison or
-// assignment with mSpanState.
+// mSpanStateBox holds an atomic.Uint8 to provide atomic operations on
+// an mSpanState. This is a separate type to disallow accidental comparison
+// or assignment with mSpanState.
 type mSpanStateBox struct {
-	s mSpanState
+	s atomic.Uint8
 }
 
 func (b *mSpanStateBox) set(s mSpanState) {
-	atomic.Store8((*uint8)(&b.s), uint8(s))
+	b.s.Store(uint8(s))
 }
 
 func (b *mSpanStateBox) get() mSpanState {
-	return mSpanState(atomic.Load8((*uint8)(&b.s)))
+	return mSpanState(b.s.Load())
 }
 
 // mSpanList heads a linked list of spans.