diff --git a/src/can/def.rs b/src/can/def.rs
index c7953e6492..f8d3ec5407 100644
--- a/src/can/def.rs
+++ b/src/can/def.rs
@@ -457,14 +457,8 @@ fn canonicalize_def<'a>(
             // TODO remove this clone
             *found_rigids = found_rigids.clone().union(ftv_sendmap);
 
-            let fname: String = if let Pattern::Identifier(_, name) = loc_can_pattern.value {
-                (Into::<Box<str>>::into(name)).to_string()
-            } else {
-                panic!("TODO support other patterns too (requires changing FromAnnotation)");
-            };
-
             let annotation_expected = FromAnnotation(
-                fname,
+                loc_can_pattern,
                 can_annotation.arity(),
                 AnnotationSource::TypedBody,
                 can_annotation,
@@ -503,19 +497,9 @@ fn canonicalize_def<'a>(
             // identifier (e.g. `f = \x -> ...`), then this symbol can be tail-called.
             let outer_identifier = env.tailcallable_symbol.clone();
 
-            // TODO ensure TypedDef has a pattern identifier?
-            // e.g. in elm, you can't type
-            //
-            // (foo, bar) : (Int, Bool)
-            // implicitly, that is the case here too
-            let mut fname = "invalid name".to_string();
-
-            if let (
-                &ast::Pattern::Identifier(ref name),
-                &Pattern::Identifier(_, ref defined_symbol),
-            ) = (&loc_pattern.value, &loc_can_pattern.value)
+            if let (&ast::Pattern::Identifier(_), &Pattern::Identifier(_, ref defined_symbol)) =
+                (&loc_pattern.value, &loc_can_pattern.value)
             {
-                fname = (*name).to_string();
                 env.tailcallable_symbol = Some(defined_symbol.clone());
                 variables_by_symbol.insert(defined_symbol.clone(), expr_var);
             };
@@ -535,7 +519,7 @@ fn canonicalize_def<'a>(
             let new_rtv = rigids.clone().union(new_rigids);
 
             let annotation_expected = FromAnnotation(
-                fname,
+                loc_can_pattern.clone(),
                 can_annotation.arity(),
                 AnnotationSource::TypedBody,
                 can_annotation,
diff --git a/src/types.rs b/src/types.rs
index 23d232c7fc..36eb651fa0 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,4 +1,5 @@
 use crate::can::ident::{Lowercase, ModuleName, Uppercase};
+use crate::can::pattern::Pattern;
 use crate::can::symbol::Symbol;
 use crate::collections::{MutSet, SendMap};
 use crate::operator::{ArgSide, BinOp};
@@ -189,10 +190,10 @@ impl Type {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum Expected<T> {
     NoExpectation(T),
-    FromAnnotation(String, usize, AnnotationSource, T),
+    FromAnnotation(Located<Pattern>, usize, AnnotationSource, T),
     ForReason(Reason, T, Region),
 }
 
@@ -253,7 +254,7 @@ pub enum Reason {
     ElemInList,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 #[allow(clippy::large_enum_variant)]
 pub enum Constraint {
     Eq(Type, Expected<Type>, Region),
@@ -277,7 +278,7 @@ pub enum PatternCategory {
     Float,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq)]
 pub struct LetConstraint {
     pub rigid_vars: Vec<Variable>,
     pub flex_vars: Vec<Variable>,