diff --git a/CMakeLists.txt b/CMakeLists.txt
index ba8de2bd..a3f40c3a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -200,7 +200,9 @@ if (USE_TLS AND USE_MBED_TLS)
   endif()
 endif()
 
-find_package(ZLIB)
+if (NOT ZLIB_FOUND)
+  find_package(ZLIB)
+endif()
 if (ZLIB_FOUND)
   include_directories(${ZLIB_INCLUDE_DIRS})
   target_link_libraries(ixwebsocket ${ZLIB_LIBRARIES})