diff --git a/ssa/interp/ops.go b/ssa/interp/ops.go
index b1eed033..50bfd33f 100644
--- a/ssa/interp/ops.go
+++ b/ssa/interp/ops.go
@@ -881,13 +881,12 @@ func unop(instr *ssa.UnOp, x value) value {
 func typeAssert(i *interpreter, instr *ssa.TypeAssert, itf iface) value {
 	var v value
 	err := ""
-	if idst, ok := instr.AssertedType.Underlying().(*types.Interface); ok {
-		if itf.t == nil {
-			err = fmt.Sprintf("interface conversion: interface is nil, not %s", instr.AssertedType)
-		} else {
-			v = itf
-			err = checkInterface(i, idst, itf)
-		}
+	if itf.t == nil {
+		err = fmt.Sprintf("interface conversion: interface is nil, not %s", instr.AssertedType)
+
+	} else if idst, ok := instr.AssertedType.Underlying().(*types.Interface); ok {
+		v = itf
+		err = checkInterface(i, idst, itf)
 
 	} else if types.IsIdentical(itf.t, instr.AssertedType) {
 		v = copyVal(itf.v) // extract value