diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index f4ee7960f1074..6655b32fad392 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -30395,6 +30395,9 @@ namespace ts {
                     assignBindingElementTypes(declaration.name);
                 }
             }
+            else if (type) {
+                Debug.assertEqual(links.type, type, "Parameter symbol already has a cached type which differs from newly assigned type");
+            }
         }
 
         // When contextual typing assigns a type to a parameter that contains a binding pattern, we also need to push