diff --git a/lib/AST/MicrosoftCXXABI.cpp b/lib/AST/MicrosoftCXXABI.cpp
index 6847ee16f7af780f04c29c4482072bfecdde82ff..ff84fa5c22526554853c99c7059d9fc79a1df364 100644
--- a/lib/AST/MicrosoftCXXABI.cpp
+++ b/lib/AST/MicrosoftCXXABI.cpp
@@ -135,8 +135,8 @@ public:
   }
 
   TypedefNameDecl *getTypedefNameForUnnamedTagDecl(const TagDecl *TD) override {
-    return UnnamedTagDeclToTypedefNameDecl[const_cast<TagDecl *>(
-        TD->getCanonicalDecl())];
+    return UnnamedTagDeclToTypedefNameDecl.lookup(
+        const_cast<TagDecl *>(TD->getCanonicalDecl()));
   }
 
   void addDeclaratorForUnnamedTagDecl(TagDecl *TD,
@@ -149,8 +149,8 @@ public:
   }
 
   DeclaratorDecl *getDeclaratorForUnnamedTagDecl(const TagDecl *TD) override {
-    return UnnamedTagDeclToDeclaratorDecl[const_cast<TagDecl *>(
-        TD->getCanonicalDecl())];
+    return UnnamedTagDeclToDeclaratorDecl.lookup(
+        const_cast<TagDecl *>(TD->getCanonicalDecl()));
   }
 
   MangleNumberingContext *createMangleNumberingContext() const override {