diff --git a/src/liblzma/api/lzma/filter.h b/src/liblzma/api/lzma/filter.h
index 4c83b2b3..d5054c24 100644
--- a/src/liblzma/api/lzma/filter.h
+++ b/src/liblzma/api/lzma/filter.h
@@ -589,7 +589,7 @@ extern LZMA_API(lzma_ret) lzma_filter_flags_decode(
  *                          be LZMA_FILTERS_MAX + 1 (that is, five) elements
  *                          in the array. The old contents are ignored so it
  *                          doesn't need to be initialized. This array is
- *                          modified only if this function returns LZMA_OK.
+ *                          modified only if this function returns NULL.
  *                          Once the allocated filter options are no longer
  *                          needed, lzma_filters_free() can be used to free the
  *                          options (it doesn't free the filters array itself).