diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index bb0148ae31..05ac6866d9 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -1326,11 +1326,13 @@ qt_internal_add_docs(Core
     doc/qtcore.qdocconf
 )
 
-qt_internal_add_3rdparty_header_module(ZlibPrivate
-    EXTERNAL_HEADERS
-        ../3rdparty/zlib/src/zlib.h
-        ../3rdparty/zlib/src/zconf.h
-)
+if(NOT QT_FEATURE_system_zlib)
+    qt_internal_add_3rdparty_header_module(ZlibPrivate
+        EXTERNAL_HEADERS
+            ../3rdparty/zlib/src/zlib.h
+            ../3rdparty/zlib/src/zconf.h
+    )
+endif()
 
 qt_internal_add_optimize_full_flags()