diff --git a/crsn/src/asm/parse/parse_data.rs b/crsn/src/asm/parse/parse_data.rs
index 56bc250..8b9bbf4 100644
--- a/crsn/src/asm/parse/parse_data.rs
+++ b/crsn/src/asm/parse/parse_data.rs
@@ -95,12 +95,25 @@ pub fn parse_data_disp(tok: Option<Sexp>, pcx: &ParserContext) -> Result<DataDis
                 if let Some(val) = pstate.reg_aliases.get(reference) {
                     Ok(DataDisp::ObjectPtr(*val))
                 } else {
-                    Ok(DataDisp::ObjectPtr(reg::parse_reg(reference)?))
+                    let reg = reg::parse_reg(reference)?;
+
+                    if pstate.reg_aliases.values().find(|v| **v == reg).is_some() {
+                        Err(CrsnError::Parse(format!("Sym exists for register {}, direct access denied. Unsym it if needed.", reg).into()))
+                    } else {
+                        Ok(DataDisp::ObjectPtr(reg))
+                    }
                 }
             } else if s.starts_with(|c: char| c.is_ascii_digit()) {
                 Ok(DataDisp::Immediate(unsafe { std::mem::transmute(parse_i64(s)?) }))
             } else {
-                Ok(DataDisp::Register(reg::parse_reg(s)?))
+                let reg = reg::parse_reg(s)?;
+
+                let pstate = pcx.state.borrow();
+                if pstate.reg_aliases.values().find(|v| **v == reg).is_some() {
+                    Err(CrsnError::Parse(format!("Sym exists for register {}, direct access denied. Unsym it if needed.", reg).into()))
+                } else {
+                    Ok(DataDisp::Register(reg))
+                }
             }
         }
         _ => {
diff --git a/crsn/src/builtin/parse.rs b/crsn/src/builtin/parse.rs
index a75f3dd..779bea6 100644
--- a/crsn/src/builtin/parse.rs
+++ b/crsn/src/builtin/parse.rs
@@ -8,7 +8,7 @@ use crate::asm::parse::arg_parser::TokenParser;
 use crate::asm::parse::parse_data::{parse_constant_name, parse_label, parse_rd, parse_reg_alias, parse_value, parse_label_str};
 use crate::asm::parse::sexp_expect::expect_string_atom;
 use crate::builtin::defs::{Barrier, BuiltinOp};
-use crate::module::{CrsnExtension, ParseRes};
+use crate::module::{ParseRes};
 use crate::utils::A;
 
 
diff --git a/crsn_screen/src/exec.rs b/crsn_screen/src/exec.rs
index b29da42..1afd177 100644
--- a/crsn_screen/src/exec.rs
+++ b/crsn_screen/src/exec.rs
@@ -168,8 +168,8 @@ impl OpTrait for ScreenOp {
                                 let xval = xf.round() as u64;
                                 let yval = yf.round() as u64;
 
-                                state.write(*x, xval);
-                                state.write(*y, yval);
+                                state.write(*x, xval)?;
+                                state.write(*y, yval)?;
                             }
                         }
                     }
diff --git a/crsn_screen/src/parse.rs b/crsn_screen/src/parse.rs
index 1d10887..ea1afe2 100644
--- a/crsn_screen/src/parse.rs
+++ b/crsn_screen/src/parse.rs
@@ -1,4 +1,4 @@
-use crsn::asm::data::{Rd, RdData};
+use crsn::asm::data::{Rd};
 use crsn::asm::error::CrsnError;
 use crsn::asm::instr::op::OpKind;
 use crsn::asm::parse::arg_parser::TokenParser;
diff --git a/crsn_stacks/src/exec.rs b/crsn_stacks/src/exec.rs
index 1d29106..2a6cdc9 100644
--- a/crsn_stacks/src/exec.rs
+++ b/crsn_stacks/src/exec.rs
@@ -66,7 +66,7 @@ pub(crate) fn drop_obj(state: &mut RunState, handle: Value) -> Result<Option<()>
     Ok(stacks.store.remove(&handle).map(|_| ()))
 }
 
-fn prepare_push(mut state: &mut RunState, obj: &RdObj, src: &Rd, pushfn : impl FnOnce(&mut VecDeque<Value>, Value) -> ()) -> Result<(), Fault> {
+fn prepare_push(state: &mut RunState, obj: &RdObj, src: &Rd, pushfn : impl FnOnce(&mut VecDeque<Value>, Value) -> ()) -> Result<(), Fault> {
     state.clear_status();
     let handle = state.read_obj(*obj)?;
     let val = state.read(*src)?;