diff --git a/tree/ntuple/src/RFieldUtils.cxx b/tree/ntuple/src/RFieldUtils.cxx
index 797284973bd76..b4d6e65f1ba6f 100644
--- a/tree/ntuple/src/RFieldUtils.cxx
+++ b/tree/ntuple/src/RFieldUtils.cxx
@@ -272,6 +272,14 @@ void MapIntegerType(std::string &typeName)
       typeName = ROOT::RField<long long int>::TypeName();
    } else if (typeName == "unsigned long long" || typeName == "unsigned long long int") {
       typeName = ROOT::RField<unsigned long long int>::TypeName();
+   } else {
+      // The following two types are 64-bit integers on Windows that we can encounter during renormalization of
+      // demangled std::type_info names.
+      if (typeName == "__int64") {
+         typeName = "std::int64_t";
+      } else if (typeName == "unsigned __int64") {
+         typeName = "std::uint64_t";
+      }
    }
 }
 
diff --git a/tree/ntuple/test/ntuple_type_name.cxx b/tree/ntuple/test/ntuple_type_name.cxx
index 94dcd5450000f..cbbecb70b347f 100644
--- a/tree/ntuple/test/ntuple_type_name.cxx
+++ b/tree/ntuple/test/ntuple_type_name.cxx
@@ -86,6 +86,8 @@ TEST(RNTuple, TypeNameNormalizationById)
 
    EXPECT_EQ("std::int32_t", GetRenormalizedTypeName(typeid(signed)));
    EXPECT_EQ("std::int32_t", GetRenormalizedTypeName(typeid(std::int32_t)));
+   EXPECT_EQ("std::int64_t", GetRenormalizedTypeName(typeid(std::int64_t)));
+   EXPECT_EQ("std::uint64_t", GetRenormalizedTypeName(typeid(std::uint64_t)));
    EXPECT_EQ("double", GetRenormalizedTypeName(typeid(Double32_t)));
    EXPECT_EQ("float", GetRenormalizedTypeName(typeid(const float)));