--- CMakeLists.txt	2026-02-28 15:07:47.000000000 +0800
+++ CMakeLists.txt	2026-07-13 09:27:53.000000000 +0800
@@ -439,8 +439,7 @@
                            ${CYRUS_SASL_INCLUDE_DIR} ${CURSES_INCLUDE_DIR} ${OPENSSL_INCLUDE_DIR}
                            ${LIBUUID_HEADERS}
                            "${GENERATED_DIR}"
-                           "ext/cereal/include" "ext/cyrus-imap/lib" "ext/sqlite_modern_cpp/hdr"
-                           "ext/utfcpp/source")
+                           "ext/cyrus-imap/lib" "ext/sqlite_modern_cpp/hdr" "@PREFIX@/include/utf8cpp")
 
 # Linking
 target_link_libraries(nmail PUBLIC