diff --git a/lib/Sema/DerivedConformanceDifferentiable.cpp b/lib/Sema/DerivedConformanceDifferentiable.cpp
index 608905298baff..04c2ac6981575 100644
--- a/lib/Sema/DerivedConformanceDifferentiable.cpp
+++ b/lib/Sema/DerivedConformanceDifferentiable.cpp
@@ -786,8 +786,9 @@ deriveDifferentiable_AssociatedStruct(DerivedConformance &derived,
   }
 
   // Add a typealias declaration with the given name and underlying target
-  // struct type to the source struct.
-  auto addAssociatedTypeAliasDecl = [&](Identifier name, StructDecl *source,
+  // struct type to the source nominal type.
+  auto addAssociatedTypeAliasDecl = [&](Identifier name,
+                                        NominalTypeDecl *source,
                                         StructDecl *target) {
     auto lookup = source->lookupDirect(name);
     assert(lookup.size() < 2 &&
@@ -845,6 +846,10 @@ deriveDifferentiable_AssociatedStruct(DerivedConformance &derived,
                                allDiffableVarsStruct, allDiffableVarsStruct);
     addAssociatedTypeAliasDecl(C.Id_CotangentVector,
                                allDiffableVarsStruct, allDiffableVarsStruct);
+    addAssociatedTypeAliasDecl(C.Id_TangentVector,
+                               nominal, allDiffableVarsStruct);
+    addAssociatedTypeAliasDecl(C.Id_CotangentVector,
+                               nominal, allDiffableVarsStruct);
     TC.validateDecl(allDiffableVarsStruct);
     return parentDC->mapTypeIntoContext(
         allDiffableVarsStruct->getDeclaredInterfaceType());
diff --git a/test/AutoDiff/derived_differentiable_properties.swift b/test/AutoDiff/derived_differentiable_properties.swift
index d68b2d013463f..6e8c219112b78 100644
--- a/test/AutoDiff/derived_differentiable_properties.swift
+++ b/test/AutoDiff/derived_differentiable_properties.swift
@@ -13,8 +13,8 @@ public struct Foo : Differentiable {
 // CHECK-AST:     @_fieldwiseProductSpace typealias AllDifferentiableVariables = Foo.AllDifferentiableVariables
 // CHECK-AST:     @_fieldwiseProductSpace typealias TangentVector = Foo.AllDifferentiableVariables
 // CHECK-AST:     @_fieldwiseProductSpace typealias CotangentVector = Foo.AllDifferentiableVariables
-// CHECK-AST:   typealias TangentVector = Foo.AllDifferentiableVariables
-// CHECK-AST:   typealias CotangentVector = Foo.AllDifferentiableVariables
+// CHECK-AST:   @_fieldwiseProductSpace typealias TangentVector = Foo.AllDifferentiableVariables
+// CHECK-AST:   @_fieldwiseProductSpace typealias CotangentVector = Foo.AllDifferentiableVariables
 
 // CHECK-SILGEN-LABEL: // Foo.a.getter
 // CHECK-SILGEN: sil [transparent] [serialized] [differentiable source 0 wrt 0] @$s33derived_differentiable_properties3FooV1aSfvg : $@convention(method) (Foo) -> Float