diff --git a/src/passes/GlobalTypeOptimization.cpp b/src/passes/GlobalTypeOptimization.cpp
index 6316dc7e57e..c038a7a0a06 100644
--- a/src/passes/GlobalTypeOptimization.cpp
+++ b/src/passes/GlobalTypeOptimization.cpp
@@ -444,11 +444,13 @@ struct GlobalTypeOptimization : public Pass {
 
             // Clear the old names and write the new ones.
             nameInfo.fieldNames.clear();
-            for (Index i = 0; i < oldFieldNames.size(); i++) {
+            for (Index i = 0; i < indexesAfterRemoval.size(); i++) {
               auto newIndex = indexesAfterRemoval[i];
-              if (newIndex != RemovedField && oldFieldNames.count(i)) {
-                assert(oldFieldNames[i].is());
-                nameInfo.fieldNames[newIndex] = oldFieldNames[i];
+              if (newIndex != RemovedField) {
+                auto iter = oldFieldNames.find(i);
+                if (iter != oldFieldNames.end()) {
+                  nameInfo.fieldNames[newIndex] = iter->second;
+                }
               }
             }
           }
diff --git a/test/lit/passes/gto-removals.wast b/test/lit/passes/gto-removals.wast
index 9dbb712bd28..814712bccc4 100644
--- a/test/lit/passes/gto-removals.wast
+++ b/test/lit/passes/gto-removals.wast
@@ -1675,3 +1675,45 @@
     )
   )
 )
+
+(module
+  ;; A struct with partial names: only some fields are named. We should still
+  ;; update names properly when removing and reordering.
+
+  ;; CHECK:      (rec
+  ;; CHECK-NEXT:  (type $struct (sub (struct (field (mut i32)) (field $named (mut i32)))))
+  (type $struct (sub (struct (field (mut i32)) (field (mut i32)) (field $named (mut i32)) (field (mut i32)) (field (mut i32)))))
+
+  ;; CHECK:       (type $1 (func (param (ref $struct))))
+
+  ;; CHECK:      (func $func (type $1) (param $x (ref $struct))
+  ;; CHECK-NEXT:  (struct.set $struct 0
+  ;; CHECK-NEXT:   (local.get $x)
+  ;; CHECK-NEXT:   (struct.get $struct 0
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT:  (struct.set $struct $named
+  ;; CHECK-NEXT:   (local.get $x)
+  ;; CHECK-NEXT:   (struct.get $struct $named
+  ;; CHECK-NEXT:    (local.get $x)
+  ;; CHECK-NEXT:   )
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $func (param $x (ref $struct))
+    ;; Use fields 1 and 2.
+    (struct.set $struct 1
+      (local.get $x)
+      (struct.get $struct 1
+        (local.get $x)
+      )
+    )
+    (struct.set $struct 2
+      (local.get $x)
+      (struct.get $struct 2
+        (local.get $x)
+      )
+    )
+  )
+)
+