diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 4829c5f5fc..bb401e805b 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -2549,7 +2549,7 @@ func (s *state) expr(n *Node) *ssa.Value {
 		return s.load(n.Type, addr)
 
 	case ODEREF:
-		p := s.exprPtr(n.Left, false, n.Pos)
+		p := s.exprPtr(n.Left, n.Left.Bounded(), n.Pos)
 		return s.load(n.Type, p)
 
 	case ODOT:
diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index 1accfbc825..7805079a63 100644
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -1897,6 +1897,9 @@ func itabType(itab *Node) *Node {
 // The concrete type must be known to have type t.
 // It follows the pointer if !isdirectiface(t).
 func ifaceData(n *Node, t *types.Type) *Node {
+	if t.IsInterface() {
+		Fatalf("ifaceData interface: %v", t)
+	}
 	ptr := nodSym(OIDATA, n, nil)
 	if isdirectiface(t) {
 		ptr.Type = t
diff --git a/src/cmd/compile/internal/gc/swt.go b/src/cmd/compile/internal/gc/swt.go
index 0d5df2e0bd..6c931f2dab 100644
--- a/src/cmd/compile/internal/gc/swt.go
+++ b/src/cmd/compile/internal/gc/swt.go
@@ -540,10 +540,14 @@ func walkTypeSwitch(sw *Node) {
 			caseVar = ncase.Rlist.First()
 		}
 
-		// For single-type cases, we initialize the case
-		// variable as part of the type assertion; but in
-		// other cases, we initialize it in the body.
-		singleType := ncase.List.Len() == 1 && ncase.List.First().Op == OTYPE
+		// For single-type cases with an interface type,
+		// we initialize the case variable as part of the type assertion.
+		// In other cases, we initialize it in the body.
+		var singleType *types.Type
+		if ncase.List.Len() == 1 && ncase.List.First().Op == OTYPE {
+			singleType = ncase.List.First().Type
+		}
+		caseVarInitialized := false
 
 		label := autolabel(".s")
 		jmp := npos(ncase.Pos, nodSym(OGOTO, nil, label))
@@ -564,18 +568,27 @@ func walkTypeSwitch(sw *Node) {
 				continue
 			}
 
-			if singleType {
+			if singleType != nil && singleType.IsInterface() {
 				s.Add(n1.Type, caseVar, jmp)
+				caseVarInitialized = true
 			} else {
 				s.Add(n1.Type, nil, jmp)
 			}
 		}
 
 		body.Append(npos(ncase.Pos, nodSym(OLABEL, nil, label)))
-		if caseVar != nil && !singleType {
+		if caseVar != nil && !caseVarInitialized {
+			val := s.facename
+			if singleType != nil {
+				// We have a single concrete type. Extract the data.
+				if singleType.IsInterface() {
+					Fatalf("singleType interface should have been handled in Add")
+				}
+				val = ifaceData(s.facename, singleType)
+			}
 			l := []*Node{
 				nodl(ncase.Pos, ODCL, caseVar, nil),
-				nodl(ncase.Pos, OAS, caseVar, s.facename),
+				nodl(ncase.Pos, OAS, caseVar, val),
 			}
 			typecheckslice(l, ctxStmt)
 			body.Append(l...)
diff --git a/test/writebarrier.go b/test/writebarrier.go
index 8cd559c190..dbf0b6dde2 100644
--- a/test/writebarrier.go
+++ b/test/writebarrier.go
@@ -148,12 +148,12 @@ func f16(x []T8, y T8) []T8 {
 func t1(i interface{}) **int {
 	// From issue 14306, make sure we have write barriers in a type switch
 	// where the assigned variable escapes.
-	switch x := i.(type) { // ERROR "write barrier"
-	case *int:
+	switch x := i.(type) {
+	case *int: // ERROR "write barrier"
 		return &x
 	}
-	switch y := i.(type) { // no write barrier here
-	case **int:
+	switch y := i.(type) {
+	case **int: // no write barrier here
 		return y
 	}
 	return nil