diff --git a/crates/ailang-check/src/lib.rs b/crates/ailang-check/src/lib.rs
index 57e81d9..08e2840 100644
--- a/crates/ailang-check/src/lib.rs
+++ b/crates/ailang-check/src/lib.rs
@@ -475,9 +475,8 @@ fn check_type_def(td: &TypeDef, env: &Env) -> Result<()> {
 fn check_type_well_formed(t: &Type, env: &Env) -> Result<()> {
     match t {
         Type::Con { name } => {
-            if matches!(name.as_str(), "Int" | "Bool" | "Unit" | "Str") {
-                Ok(())
-            } else if env.types.contains_key(name) {
+            let is_primitive = matches!(name.as_str(), "Int" | "Bool" | "Unit" | "Str");
+            if is_primitive || env.types.contains_key(name) {
                 Ok(())
             } else {
                 Err(CheckError::UnknownType(name.clone()))
diff --git a/crates/ailang-codegen/src/lib.rs b/crates/ailang-codegen/src/lib.rs
index 094a0a8..f7618a8 100644
--- a/crates/ailang-codegen/src/lib.rs
+++ b/crates/ailang-codegen/src/lib.rs
@@ -154,7 +154,7 @@ pub fn lower_workspace(ws: &Workspace) -> Result<String> {
     // Globals: per module, alphabetically over module names (BTreeMap order),
     // then insertion order per module.
     let mut emitted_global = false;
-    for (_mname, entries) in &all_strings {
+    for entries in all_strings.values() {
         for (name, content) in entries {
             let escaped = ll_string_literal(content);
             let len = c_byte_len(content);
@@ -1086,7 +1086,6 @@ impl<'a> Emitter<'a> {
             &mut captures_set,
             &builtins,
             &top_level,
-            &self.import_map,
         );
 
         // Outer scope provides every capture as a local — assert and
@@ -1251,7 +1250,6 @@ impl<'a> Emitter<'a> {
         captures_set: &mut BTreeSet<String>,
         builtins: &BTreeSet<&str>,
         top_level: &BTreeSet<String>,
-        import_map: &BTreeMap<String, String>,
     ) {
         match t {
             Term::Lit { .. } => {}
@@ -1273,36 +1271,36 @@ impl<'a> Emitter<'a> {
                 }
             }
             Term::App { callee, args } => {
-                Self::collect_captures(callee, bound, captures, captures_set, builtins, top_level, import_map);
+                Self::collect_captures(callee, bound, captures, captures_set, builtins, top_level);
                 for a in args {
-                    Self::collect_captures(a, bound, captures, captures_set, builtins, top_level, import_map);
+                    Self::collect_captures(a, bound, captures, captures_set, builtins, top_level);
                 }
             }
             Term::Let { name, value, body } => {
-                Self::collect_captures(value, bound, captures, captures_set, builtins, top_level, import_map);
+                Self::collect_captures(value, bound, captures, captures_set, builtins, top_level);
                 let inserted = bound.insert(name.clone());
-                Self::collect_captures(body, bound, captures, captures_set, builtins, top_level, import_map);
+                Self::collect_captures(body, bound, captures, captures_set, builtins, top_level);
                 if inserted {
                     bound.remove(name);
                 }
             }
             Term::If { cond, then, else_ } => {
-                Self::collect_captures(cond, bound, captures, captures_set, builtins, top_level, import_map);
-                Self::collect_captures(then, bound, captures, captures_set, builtins, top_level, import_map);
-                Self::collect_captures(else_, bound, captures, captures_set, builtins, top_level, import_map);
+                Self::collect_captures(cond, bound, captures, captures_set, builtins, top_level);
+                Self::collect_captures(then, bound, captures, captures_set, builtins, top_level);
+                Self::collect_captures(else_, bound, captures, captures_set, builtins, top_level);
             }
             Term::Do { args, .. } => {
                 for a in args {
-                    Self::collect_captures(a, bound, captures, captures_set, builtins, top_level, import_map);
+                    Self::collect_captures(a, bound, captures, captures_set, builtins, top_level);
                 }
             }
             Term::Ctor { args, .. } => {
                 for a in args {
-                    Self::collect_captures(a, bound, captures, captures_set, builtins, top_level, import_map);
+                    Self::collect_captures(a, bound, captures, captures_set, builtins, top_level);
                 }
             }
             Term::Match { scrutinee, arms } => {
-                Self::collect_captures(scrutinee, bound, captures, captures_set, builtins, top_level, import_map);
+                Self::collect_captures(scrutinee, bound, captures, captures_set, builtins, top_level);
                 for arm in arms {
                     let mut pat_bindings = Vec::new();
                     Self::pattern_bound_names(&arm.pat, &mut pat_bindings);
@@ -1312,7 +1310,7 @@ impl<'a> Emitter<'a> {
                             newly_bound.push(n.clone());
                         }
                     }
-                    Self::collect_captures(&arm.body, bound, captures, captures_set, builtins, top_level, import_map);
+                    Self::collect_captures(&arm.body, bound, captures, captures_set, builtins, top_level);
                     for n in newly_bound {
                         bound.remove(&n);
                     }
@@ -1327,14 +1325,14 @@ impl<'a> Emitter<'a> {
                         newly_bound.push(p.clone());
                     }
                 }
-                Self::collect_captures(body, bound, captures, captures_set, builtins, top_level, import_map);
+                Self::collect_captures(body, bound, captures, captures_set, builtins, top_level);
                 for n in newly_bound {
                     bound.remove(&n);
                 }
             }
             Term::Seq { lhs, rhs } => {
-                Self::collect_captures(lhs, bound, captures, captures_set, builtins, top_level, import_map);
-                Self::collect_captures(rhs, bound, captures, captures_set, builtins, top_level, import_map);
+                Self::collect_captures(lhs, bound, captures, captures_set, builtins, top_level);
+                Self::collect_captures(rhs, bound, captures, captures_set, builtins, top_level);
             }
         }
     }
@@ -1546,7 +1544,7 @@ fn builtin_binop(name: &str) -> Option<(&'static str, &'static str)> {
 }
 
 fn c_byte_len(s: &str) -> usize {
-    s.as_bytes().len() + 1 // + NUL
+    s.len() + 1 // + NUL terminator
 }
 
 /// Escapes a string for LLVM IR `c"..."`. All bytes outside