diff --git a/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.d.hpp b/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.d.hpp
index ac6e97648d6..52e967d89b2 100644
--- a/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.d.hpp
+++ b/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.d.hpp
@@ -38,7 +38,7 @@ struct GeneralCategoryGroup {
 
   inline static icu4x::GeneralCategoryGroup empty();
 
-  inline icu4x::GeneralCategoryGroup union(icu4x::GeneralCategoryGroup other);
+  inline icu4x::GeneralCategoryGroup union_(icu4x::GeneralCategoryGroup other);
 
   inline icu4x::GeneralCategoryGroup intersection(icu4x::GeneralCategoryGroup other);
 
diff --git a/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.hpp b/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.hpp
index 47575373205..8e8194a18bd 100644
--- a/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.hpp
+++ b/ffi/capi/bindings/cpp/icu4x/GeneralCategoryGroup.hpp
@@ -71,7 +71,7 @@ inline icu4x::GeneralCategoryGroup icu4x::GeneralCategoryGroup::empty() {
   return icu4x::GeneralCategoryGroup::FromFFI(result);
 }
 
-inline icu4x::GeneralCategoryGroup icu4x::GeneralCategoryGroup::union(icu4x::GeneralCategoryGroup other) {
+inline icu4x::GeneralCategoryGroup icu4x::GeneralCategoryGroup::union_(icu4x::GeneralCategoryGroup other) {
   auto result = icu4x::capi::icu4x_GeneralCategoryGroup_union_mv1(this->AsFFI(),
     other.AsFFI());
   return icu4x::GeneralCategoryGroup::FromFFI(result);
diff --git a/ffi/capi/src/properties_enums.rs b/ffi/capi/src/properties_enums.rs
index 7bb80ba4be3..190acad05d4 100644
--- a/ffi/capi/src/properties_enums.rs
+++ b/ffi/capi/src/properties_enums.rs
@@ -1782,6 +1782,7 @@ pub mod ffi {
             props::GeneralCategoryGroup::empty().into()
         }
         #[diplomat::rust_link(icu::properties::props::GeneralCategoryGroup::union, FnInStruct)]
+        #[diplomat::attr(any(c, cpp), rename = "union_")]
         pub fn union(self, other: Self) -> Self {
             self.into_props_group()
                 .union(other.into_props_group())