diff -Naur icu_collections-1.5.0-original/src/codepointinvlist/cpinvlist.rs icu_collections-1.5.0/src/codepointinvlist/cpinvlist.rs
--- icu_collections-1.5.0-original/src/codepointinvlist/cpinvlist.rs	2006-07-23 21:21:28.000000000 -0400
+++ icu_collections-1.5.0/src/codepointinvlist/cpinvlist.rs	2024-11-23 10:42:53.464004825 -0500
@@ -1034,6 +1034,8 @@
     }
 
     #[test]
+    // Downstream-only: unconditionally disable this because we lack postcard
+    #[cfg(any())]
     fn test_serde_with_postcard_roundtrip() -> Result<(), postcard::Error> {
         let set = CodePointInversionList::bmp();
         let set_serialized: Vec<u8> = postcard::to_allocvec(&set).unwrap();
diff -Naur icu_collections-1.5.0-original/src/codepointtrie/cptrie.rs icu_collections-1.5.0/src/codepointtrie/cptrie.rs
--- icu_collections-1.5.0-original/src/codepointtrie/cptrie.rs	2006-07-23 21:21:28.000000000 -0400
+++ icu_collections-1.5.0/src/codepointtrie/cptrie.rs	2024-11-23 10:42:58.801073739 -0500
@@ -1082,6 +1082,8 @@
 
     #[test]
     #[cfg(feature = "serde")]
+    // Downstream-only: unconditionally disable this because we lack postcard
+    #[cfg(any())]
     fn test_serde_with_postcard_roundtrip() -> Result<(), postcard::Error> {
         let trie = crate::codepointtrie::planes::get_planes_trie();
         let trie_serialized: Vec<u8> = postcard::to_allocvec(&trie).unwrap();