diff --git a/src/port/pg_bitutils.c b/src/port/pg_bitutils.c
index 60fb55af53..8d9f5be32a 100644
--- a/src/port/pg_bitutils.c
+++ b/src/port/pg_bitutils.c
@@ -56,7 +56,7 @@ const uint8 pg_leftmost_one_pos[256] = {
  * left-most the 7th bit.  The 0th entry of the array should not be used.
  *
  * Note: this is not used by the functions in pg_bitutils.h when
- * HAVE_BUILTIN_CTZ is defined, but we provide it anyway, so that
+ * HAVE__BUILTIN_CTZ is defined, but we provide it anyway, so that
  * extensions possibly compiled with a different compiler can use it.
  */
 const uint8 pg_rightmost_one_pos[256] = {