diff --git a/CMakeLists.txt b/CMakeLists.txt
index a94d9c91..b3a02386 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -120,6 +120,10 @@ if(${CMAKE_SYSTEM_NAME} STREQUAL FreeBSD)
   target_link_libraries(ccls PRIVATE thr)
 endif()
 
+if(LLVM_ENABLE_ZLIB)
+  find_package(ZLIB)
+endif()
+
 ### Definitions
 
 # Find Clang resource directory with Clang executable.