diff --git a/src/cmd/compile/internal/gc/bimport.go b/src/cmd/compile/internal/gc/bimport.go
index d7d48cb07e..e7308df2a8 100644
--- a/src/cmd/compile/internal/gc/bimport.go
+++ b/src/cmd/compile/internal/gc/bimport.go
@@ -533,7 +533,7 @@ func (p *importer) typ() *Type {
 			t = Types[TINTER]
 		} else {
 			t = p.newtyp(TINTER)
-			t.SetFields(ml)
+			t.SetInterface(ml)
 		}
 		checkwidth(t)
 
diff --git a/src/cmd/compile/internal/gc/dcl.go b/src/cmd/compile/internal/gc/dcl.go
index 583c440259..6fca2062d0 100644
--- a/src/cmd/compile/internal/gc/dcl.go
+++ b/src/cmd/compile/internal/gc/dcl.go
@@ -897,7 +897,7 @@ func tointerface0(t *Type, l []*Node) *Type {
 		}
 	}
 	sort.Sort(methcmp(fields))
-	t.SetFields(fields)
+	t.SetInterface(fields)
 
 	checkdupfields("method", t)
 	checkwidth(t)
diff --git a/src/cmd/compile/internal/gc/type.go b/src/cmd/compile/internal/gc/type.go
index b1eb05764e..e4841708f6 100644
--- a/src/cmd/compile/internal/gc/type.go
+++ b/src/cmd/compile/internal/gc/type.go
@@ -865,6 +865,7 @@ func (t *Type) FieldSlice() []*Field {
 
 // SetFields sets struct/interface type t's fields/methods to fields.
 func (t *Type) SetFields(fields []*Field) {
+	t.wantEtype(TSTRUCT)
 	for _, f := range fields {
 		// If type T contains a field F with a go:notinheap
 		// type, then T must also be go:notinheap. Otherwise,
@@ -879,6 +880,11 @@ func (t *Type) SetFields(fields []*Field) {
 	t.Fields().Set(fields)
 }
 
+func (t *Type) SetInterface(methods []*Field) {
+	t.wantEtype(TINTER)
+	t.Fields().Set(methods)
+}
+
 func (t *Type) isDDDArray() bool {
 	if t.Etype != TARRAY {
 		return false
diff --git a/src/cmd/compile/internal/gc/universe.go b/src/cmd/compile/internal/gc/universe.go
index a54a05a8f5..b6fbd2d566 100644
--- a/src/cmd/compile/internal/gc/universe.go
+++ b/src/cmd/compile/internal/gc/universe.go
@@ -382,7 +382,7 @@ func makeErrorInterface() *Type {
 	field.Type = f
 
 	t := typ(TINTER)
-	t.SetFields([]*Field{field})
+	t.SetInterface([]*Field{field})
 	return t
 }