diff --git a/ic10emu/build.rs b/ic10emu/build.rs
index 07c4709..c7a53ca 100644
--- a/ic10emu/build.rs
+++ b/ic10emu/build.rs
@@ -3,8 +3,8 @@ use std::{
     collections::HashSet,
     env,
     fs::{self, File},
-    io::{BufRead, BufReader, BufWriter, Write},
-    path::{Path, PathBuf},
+    io::{BufWriter, Write},
+    path::Path,
 };
 
 fn write_logictypes(logictypes_grammar: &mut HashSet<String>) {
diff --git a/ic10emu/src/grammar.rs b/ic10emu/src/grammar.rs
index 9bc2af5..7341d53 100644
--- a/ic10emu/src/grammar.rs
+++ b/ic10emu/src/grammar.rs
@@ -518,6 +518,11 @@ impl FromStr for Operand {
                         name: s.to_string(),
                         value: *val as f64,
                     }))
+                } else if let Some(val) = SLOT_TYPE_LOOKUP.get(s) {
+                    Ok(Operand::LogicType(LogicType {
+                        name: s.to_string(),
+                        value: *val as f64,
+                    }))
                 } else if let Some(val) = BATCH_MODE_LOOKUP.get(s) {
                     Ok(Operand::LogicType(LogicType {
                         name: s.to_string(),
diff --git a/ic10emu/src/interpreter.rs b/ic10emu/src/interpreter.rs
index e88e47b..8fe3b48 100644
--- a/ic10emu/src/interpreter.rs
+++ b/ic10emu/src/interpreter.rs
@@ -156,7 +156,7 @@ impl IC {
     }
 
     /// processes one line of the contained program
-    pub fn step(&mut self, housing: &mut crate::Device, vm: &mut crate::VM) -> Result<(), ICError> {
+    pub fn step(&mut self, _housing: &mut crate::Device, _vm: &mut crate::VM) -> Result<(), ICError> {
         use grammar::InstructionOp::*;
         use grammar::*;
         use ICError::*;