diff --git a/CMakeLists.txt b/CMakeLists.txt
index 62d9f292c..4ee036861 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -83,7 +83,7 @@ OPTION( ASSIMP_NO_EXPORT
 )
 OPTION( ASSIMP_BUILD_ZLIB
   "Build your own zlib"
-  OFF
+  ON
 )
 OPTION( ASSIMP_BUILD_ASSIMP_TOOLS
   "If the supplementary tools for Assimp are built in addition to the library."