diff --git a/compiler/compiler.go b/compiler/compiler.go
index 1a56c98c..816f91d8 100644
--- a/compiler/compiler.go
+++ b/compiler/compiler.go
@@ -2225,7 +2225,7 @@ func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
 		if err != nil {
 			return llvm.Value{}, err
 		}
-		return c.parseBinOp(expr.Op, expr.X.Type().Underlying(), x, y)
+		return c.parseBinOp(expr.Op, expr.X.Type(), x, y)
 	case *ssa.Call:
 		// Passing the current task here to the subroutine. It is only used when
 		// the subroutine is blocking.
@@ -2711,7 +2711,7 @@ func (c *Compiler) parseExpr(frame *Frame, expr ssa.Value) (llvm.Value, error) {
 }
 
 func (c *Compiler) parseBinOp(op token.Token, typ types.Type, x, y llvm.Value) (llvm.Value, error) {
-	switch typ := typ.(type) {
+	switch typ := typ.Underlying().(type) {
 	case *types.Basic:
 		if typ.Info()&types.IsInteger != 0 {
 			// Operations on integers
diff --git a/testdata/binop.go b/testdata/binop.go
index 64a33953..e98545f9 100644
--- a/testdata/binop.go
+++ b/testdata/binop.go
@@ -58,8 +58,10 @@ var s2 = Struct2{"foo", 0.0, 5}
 
 var a1 = [2]int{1, 2}
 
+type Int int
+
 type Struct1 struct {
-	i int
+	i Int
 	b bool
 }