diff --git a/compiler/constrain/src/expr.rs b/compiler/constrain/src/expr.rs
index adfdd50005..7e2be731da 100644
--- a/compiler/constrain/src/expr.rs
+++ b/compiler/constrain/src/expr.rs
@@ -118,8 +118,8 @@ pub fn constrain_expr(
                 let record_type = Type::Record(
                     field_types,
                     // TODO can we avoid doing Box::new on every single one of these?
-                    // For example, could we have a single lazy_static global Box they
-                    // could all share?
+                    // We can put `static EMPTY_REC: Type = Type::EmptyRec`, but that requires a
+                    // lifetime parameter on `Type`
                     Box::new(Type::EmptyRec),
                 );
                 let record_con = Eq(record_type, expected.clone(), Category::Record, region);
@@ -600,11 +600,7 @@ pub fn constrain_expr(
                 }
             }
 
-            // TODO check for exhaustiveness. If this `case` is non-exaustive, then:
-            //
-            // 1. Record a Problem.
-            // 2. Add an extra _ branch at the end which throws a runtime error.
-
+            // exhautiveness checking happens when converting to mono::Expr
             exists(vec![cond_var, *expr_var], And(constraints))
         }
         Access {
@@ -798,7 +794,6 @@ fn constrain_when_branch(
         constraints: Vec::with_capacity(1),
     };
 
-    // TODO ensure this is correct
     // TODO investigate for error messages, is it better to unify all branches with a variable,
     // then unify that variable with the expectation?
     for loc_pattern in &when_branch.patterns {
@@ -967,8 +962,7 @@ fn constrain_def(env: &Env, def: &Def, body_con: Constraint) -> Constraint {
                 expr_type,
                 annotation_expected.clone(),
                 Category::Storage,
-                // TODO proper region
-                Region::zero(),
+                annotation.region,
             ));
 
             constrain_expr(