diff --git a/Modules/_zstd/compressor.c b/Modules/_zstd/compressor.c
index 7f0558909b4422..6e61380a2db18a 100644
--- a/Modules/_zstd/compressor.c
+++ b/Modules/_zstd/compressor.c
@@ -489,7 +489,7 @@ compress_lock_held(ZstdCompressor *self, Py_buffer *data,
     return NULL;
 }
 
-#ifdef Py_DEBUG
+#ifndef NDEBUG
 static inline int
 mt_continue_should_break(ZSTD_inBuffer *in, ZSTD_outBuffer *out)
 {