diff --git a/setup.py b/setup.py
index 58675c875aa..cf6249800bd 100644
--- a/setup.py
+++ b/setup.py
@@ -166,6 +166,7 @@ def detect_openssl(prefixes):
 include_dirs = []
 library_dirs = []
 define_macros = []
+define_macros.append(('XXH_PRIVATE_API', 'YES'))  # for zstd lib (includes xxh64) and xxh64
 
 possible_openssl_prefixes = ['/usr', '/usr/local', '/usr/local/opt/openssl', '/usr/local/ssl', '/usr/local/openssl',
                              '/usr/local/borg', '/opt/local', '/opt/pkg', '/opt/homebrew/opt/openssl@1.1', ]
diff --git a/setup_xxhash.py b/setup_xxhash.py
index 244e2323b1b..74e5f38e36c 100644
--- a/setup_xxhash.py
+++ b/setup_xxhash.py
@@ -67,7 +67,10 @@ def multi_join(paths, *path_segments):
     if not use_system:
         extra_compile_args += []  # not used yet
 
+    define_macros = kwargs.get('define_macros', [])
+    #define_macros.append(('XXH_PRIVATE_API', 'YES'))
+
     ret = dict(**kwargs)
-    ret.update(dict(sources=sources, extra_compile_args=extra_compile_args,
+    ret.update(dict(sources=sources, extra_compile_args=extra_compile_args, define_macros=define_macros,
                     include_dirs=include_dirs, library_dirs=library_dirs, libraries=libraries))
     return ret