diff --git a/src/mccode_antlr/common/expression.py b/src/mccode_antlr/common/expression.py
index 01b804b..bede08f 100644
--- a/src/mccode_antlr/common/expression.py
+++ b/src/mccode_antlr/common/expression.py
@@ -500,7 +500,7 @@ def __post_init__(self):
 
     def as_type(self, pdt):
         value = [x.as_type(pdt) for x in self.value]
-        return UnaryOp(self.op, value)
+        return UnaryOp(data_type=self.data_type, style=self.style, op=self.op, value=value)
 
     def _str_repr_(self, vstr):
         c_style = self.style == OpStyle.C
diff --git a/tests/test_expression.py b/tests/test_expression.py
index d2aadea..9d81648 100644
--- a/tests/test_expression.py
+++ b/tests/test_expression.py
@@ -267,6 +267,15 @@ def test_UnaryOp(self):
         not_val.style = OpStyle.PYTHON
         self.assertEqual(str(not_val), 'not val')
 
+    def test_UnaryOp_as_type(self):
+        uop = UnaryOp(DataType.undefined, OpStyle.C, '__not__', Value.id('val'))
+        self.assertEqual(str(uop), '!val')
+        iop = uop.as_type(DataType.int)
+        self.assertEqual(str(iop), '!val')
+        fop = uop.as_type(DataType.float)
+        self.assertEqual(str(fop), '!val')
+
+
     def test_numeric_BinaryOp(self):
         f = [Value.float(x) for x in range(3)]
         i = [Value.float(x) for x in range(3)]