diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 07d42e7e2f3b3..61dd330553860 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -5873,8 +5873,14 @@ ASTContext::getSubstBuiltinTemplatePack(const TemplateArgument &ArgPack) {
 
   QualType Canon;
   TemplateArgument CanonArgPack = getCanonicalTemplateArgument(ArgPack);
-  if (!CanonArgPack.structurallyEquals(ArgPack))
+  if (!CanonArgPack.structurallyEquals(ArgPack)) {
     Canon = getSubstBuiltinTemplatePack(CanonArgPack);
+    // Refresh InsertPos, in case the recursive call above caused rehashing,
+    // which would invalidate the bucket pointer.
+    [[maybe_unused]] const auto *Nothing =
+        SubstBuiltinTemplatePackTypes.FindNodeOrInsertPos(ID, InsertPos);
+    assert(!Nothing);
+  }
 
   auto *PackType = new (*this, alignof(SubstBuiltinTemplatePackType))
       SubstBuiltinTemplatePackType(Canon, ArgPack);