diff --git a/src/runtime/atomic_pointer.go b/src/runtime/atomic_pointer.go
index bd21b49945..d54f1d6eef 100644
--- a/src/runtime/atomic_pointer.go
+++ b/src/runtime/atomic_pointer.go
@@ -15,10 +15,9 @@ import (
 // escape analysis decisions about the pointer value being stored.
 // Instead, these are wrappers around the actual atomics (casp1 and so on)
 // that use noescape to convey which arguments do not escape.
-//
-// Additionally, these functions must update the shadow heap for
-// write barrier checking.
 
+// atomicstorep performs *ptr = new atomically and invokes a write barrier.
+//
 //go:nosplit
 func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
 	atomic.Storep1(noescape(ptr), new)
diff --git a/src/runtime/internal/atomic/atomic_s390x.go b/src/runtime/internal/atomic/atomic_s390x.go
index f31f1af444..b6d3d84bdf 100644
--- a/src/runtime/internal/atomic/atomic_s390x.go
+++ b/src/runtime/internal/atomic/atomic_s390x.go
@@ -40,7 +40,7 @@ func Store64(ptr *uint64, val uint64) {
 //go:noinline
 //go:nosplit
 func Storep1(ptr unsafe.Pointer, val unsafe.Pointer) {
-	*(*unsafe.Pointer)(ptr) = val
+	*(*uintptr)(ptr) = uintptr(val)
 }
 
 //go:noescape