diff --git a/compiler/can/src/expr.rs b/compiler/can/src/expr.rs
index aa899ddeb5..4922d07424 100644
--- a/compiler/can/src/expr.rs
+++ b/compiler/can/src/expr.rs
@@ -294,12 +294,18 @@ pub struct WhenBranch {
 }
 
 impl WhenBranch {
-    pub fn region(&self) -> Region {
-        Region::across_all(
-            self.patterns
-                .iter()
-                .map(|p| &p.region)
-                .chain([self.value.region].iter()),
+    pub fn pattern_region(&self) -> Region {
+        Region::span_across(
+            &self
+                .patterns
+                .first()
+                .expect("when branch has no pattern?")
+                .region,
+            &self
+                .patterns
+                .last()
+                .expect("when branch has no pattern?")
+                .region,
         )
     }
 }
diff --git a/compiler/constrain/src/expr.rs b/compiler/constrain/src/expr.rs
index df3806a872..0833f9b914 100644
--- a/compiler/constrain/src/expr.rs
+++ b/compiler/constrain/src/expr.rs
@@ -596,7 +596,7 @@ pub fn constrain_expr(
                 Region::span_across(
                     &loc_cond.region,
                     // &branches.first().unwrap().region(),
-                    &branches.last().unwrap().region(),
+                    &branches.last().unwrap().pattern_region(),
                 )
             };