diff --git a/src/cst/expression.rs b/src/cst/expression.rs
index fe9fbe8..a45bb89 100644
--- a/src/cst/expression.rs
+++ b/src/cst/expression.rs
@@ -100,35 +100,36 @@ impl Expression {
 
     fn gen_reference_value(json: &JsonValue, context: &mut ModuleContext) -> Option<Value> {
         let (symbol, range) = Self::gen_reference_call(json, context);
-        if range.is_some() {
-            warn!("FIXME: bitfield access at CST node '{}'", json);
-        }
 
         if context.unit_ctx.data.is_some() {
             let unit_ctx = &mut context.unit_ctx;
             let raw_name_to_value = &mut unit_ctx.raw_name_to_value;
             let raw_name_to_shadow = &unit_ctx.raw_name_to_shadow;
 
-            if raw_name_to_value.contains_key(&symbol) {
-                let value = raw_name_to_value[&symbol];
+            let mut builder = UnitContext::builder(&mut unit_ctx.data);
+            let bb_head = *unit_ctx.bb_head.last().unwrap();
+            builder.append_to(bb_head);
+
+            let value = if raw_name_to_value.contains_key(&symbol) {
+                let symbol_value = raw_name_to_value[&symbol];
                 let shadow = raw_name_to_shadow.get(&symbol).cloned();
 
-                let mut builder = UnitContext::builder(&mut unit_ctx.data);
-                let bb_head = *unit_ctx.bb_head.last().unwrap();
-                builder.append_to(bb_head);
-
-                Some(match shadow {
-                    None => builder.ins().prb(value),
+                match shadow {
+                    None => builder.ins().prb(symbol_value),
                     Some(s) => builder.ins().ld(s),
-                })
+                }
             } else if context.param.contains_key(&symbol) {
-                let mut builder = UnitContext::builder(&mut unit_ctx.data);
-                let bb_head = *unit_ctx.bb_head.last().unwrap();
-                builder.append_to(bb_head);
-
-                Some(builder.ins().const_int(context.param[&symbol].clone()))
+                builder.ins().const_int(context.param[&symbol].clone())
             } else {
                 panic!("unknown error at CST node {}", json);
+            };
+
+            if range.is_some() {
+                let base = range.unwrap().1;
+                let width = range.unwrap().0 - range.unwrap().1 + 1;
+                Some(builder.ins().ext_slice(value, base, width))
+            } else {
+                Some(value)
             }
         } else {
             None