diff --git a/importer/pkginfo.go b/importer/pkginfo.go
index 12aac26b8f..a78ece5b6a 100644
--- a/importer/pkginfo.go
+++ b/importer/pkginfo.go
@@ -158,12 +158,12 @@ func (info *PackageInfo) BuiltinCallSignature(e *ast.CallExpr) *types.Signature
 		var t0, t1 types.Type
 		t0 = info.TypeOf(e) // infer arg[0] type from result type
 		if e.Ellipsis != 0 {
-			// append([]T, []T) []T
-			// append([]byte, string) []byte
+			// append(tslice, tslice...) []T
+			// append(byteslice, "foo"...) []byte
 			t1 = info.TypeOf(e.Args[1]) // no conversion
 		} else {
-			// append([]T, ...T) []T
-			t1 = t0.Underlying().(*types.Slice).Elem()
+			// append([]T, x, y, z) []T
+			t1 = t0.Underlying()
 			isVariadic = true
 		}
 		params = append(params,
@@ -175,7 +175,7 @@ func (info *PackageInfo) BuiltinCallSignature(e *ast.CallExpr) *types.Signature
 		// Note, arg0 may have any type, not necessarily tEface.
 		params = append(params,
 			types.NewVar(token.NoPos, nil, "", info.TypeOf(e.Args[0])),
-			types.NewVar(token.NoPos, nil, "", tEface))
+			types.NewVar(token.NoPos, nil, "", types.NewSlice(tEface)))
 
 	case "close":
 		params = append(params, types.NewVar(token.NoPos, nil, "", info.TypeOf(e.Args[0])))
diff --git a/ssa/builder.go b/ssa/builder.go
index 286c006b5d..0993433ab0 100644
--- a/ssa/builder.go
+++ b/ssa/builder.go
@@ -893,13 +893,8 @@ func (b *builder) emitCallArgs(fn *Function, sig *types.Signature, e *ast.CallEx
 	// f(x, y, z...): pass slice z straight through.
 	if e.Ellipsis != 0 {
 		for i, arg := range e.Args {
-			// TODO(gri): annoyingly Signature.Params doesn't
-			// reflect the slice type for a final ...T param.
-			t := sig.Params().At(i).Type()
-			if sig.IsVariadic() && i == len(e.Args)-1 {
-				t = types.NewSlice(t)
-			}
-			args = append(args, emitConv(fn, b.expr(fn, arg), t))
+			v := emitConv(fn, b.expr(fn, arg), sig.Params().At(i).Type())
+			args = append(args, v)
 		}
 		return args
 	}
@@ -935,8 +930,8 @@ func (b *builder) emitCallArgs(fn *Function, sig *types.Signature, e *ast.CallEx
 	// and construction of slice.
 	if sig.IsVariadic() {
 		varargs := args[offset+np:]
-		vt := sig.Params().At(np).Type()
-		st := types.NewSlice(vt)
+		st := sig.Params().At(np).Type().(*types.Slice)
+		vt := st.Elem()
 		if len(varargs) == 0 {
 			args = append(args, nilLiteral(st))
 		} else {