diff --git a/ext/zlib/zlib_filter.c b/ext/zlib/zlib_filter.c
index 68d9b15f7d5..0bb2f170a44 100644
--- a/ext/zlib/zlib_filter.c
+++ b/ext/zlib/zlib_filter.c
@@ -379,7 +379,7 @@ static php_stream_filter *php_zlib_filter_create(const char *filtername, zval *f
 						/* log-2 base of history window (9 - 15) */
 						SEPARATE_ZVAL(tmpzval);
 						convert_to_long_ex(tmpzval);
-						if (Z_LVAL_PP(tmpzval) < -MAX_WBITS || Z_LVAL_PP(tmpzval) > MAX_WBITS + 32) {
+						if (Z_LVAL_PP(tmpzval) < -MAX_WBITS || Z_LVAL_PP(tmpzval) > MAX_WBITS + 16) {
 							php_error_docref(NULL TSRMLS_CC, E_WARNING, "Invalid parameter give for window size. (%ld)", Z_LVAL_PP(tmpzval));
 						} else {
 							windowBits = Z_LVAL_PP(tmpzval);