diff --git a/src/cmd/compile/internal/typecheck/subr.go b/src/cmd/compile/internal/typecheck/subr.go
index bc390158465..311c5858b2c 100644
--- a/src/cmd/compile/internal/typecheck/subr.go
+++ b/src/cmd/compile/internal/typecheck/subr.go
@@ -1532,7 +1532,7 @@ func Shapify(t *types.Type, index int, tparam *types.Type) *types.Type {
 	// Note: pointers to arrays are special because of slice-to-array-pointer
 	// conversions. See issue 49295.
 	if u.Kind() == types.TPTR && u.Elem().Kind() != types.TARRAY &&
-		tparam.Bound().StructuralType() == nil {
+		tparam.Bound().StructuralType() == nil && !u.Elem().NotInHeap() {
 		u = types.Types[types.TUINT8].PtrTo()
 	}
 
diff --git a/test/typeparam/issue51733.go b/test/typeparam/issue51733.go
new file mode 100644
index 00000000000..03624f18655
--- /dev/null
+++ b/test/typeparam/issue51733.go
@@ -0,0 +1,32 @@
+// run
+
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"log"
+	"unsafe"
+)
+
+//go:notinheap
+type S struct{}
+
+func main() {
+	p := (*S)(unsafe.Pointer(uintptr(0x8000)))
+	var v any = p
+	p2 := v.(*S)
+	if p != p2 {
+		log.Fatalf("%p != %p", unsafe.Pointer(p), unsafe.Pointer(p2))
+	}
+	p2 = typeAssert[*S](v)
+	if p != p2 {
+		log.Fatalf("%p != %p from typeAssert", unsafe.Pointer(p), unsafe.Pointer(p2))
+	}
+}
+
+func typeAssert[T any](v any) T {
+	return v.(T)
+}