diff --git a/doc/api/zlib.md b/doc/api/zlib.md
index 55dc6ebb348108..408cade112d6bf 100644
--- a/doc/api/zlib.md
+++ b/doc/api/zlib.md
@@ -239,13 +239,6 @@ Compression strategy.
 * `zlib.Z_FIXED`
 * `zlib.Z_DEFAULT_STRATEGY`
 
-Possible values of the data_type field.
-
-* `zlib.Z_BINARY`
-* `zlib.Z_TEXT`
-* `zlib.Z_ASCII`
-* `zlib.Z_UNKNOWN`
-
 The deflate compression method (the only one supported in this version).
 
 * `zlib.Z_DEFLATED`