diff --git a/cmake/find_zlib.cmake b/cmake/find_zlib.cmake
index bbfc75e5e24..93e62497c25 100644
--- a/cmake/find_zlib.cmake
+++ b/cmake/find_zlib.cmake
@@ -6,6 +6,7 @@ endif ()
 
 if (NOT ZLIB_FOUND)
     set (USE_INTERNAL_ZLIB_LIBRARY 1)
+    set (ZLIB_COMPAT 1) # for zlib-ng, also enables WITH_GZFILEOP
     set (ZLIB_INCLUDE_DIR "${ClickHouse_SOURCE_DIR}/contrib/libzlib-ng" "${ClickHouse_BINARY_DIR}/contrib/libzlib-ng") # generated zconf.h
     set (ZLIB_INCLUDE_DIRS ${ZLIB_INCLUDE_DIR}) # for poco
     set (ZLIB_FOUND 1) # for poco