diff --git a/libheif/CMakeLists.txt b/libheif/CMakeLists.txt
index 359cb15032..82ca993786 100644
--- a/libheif/CMakeLists.txt
+++ b/libheif/CMakeLists.txt
@@ -131,8 +131,7 @@ endif ()
 
 option(ENABLE_EXPERIMENTAL_FEATURES "Compile experimental features and install headers with unstable API" OFF)
 if (ENABLE_EXPERIMENTAL_FEATURES)
-    list(APPEND libheif_sources api/libheif/heif_experimental.h
-            api/libheif/heif_experimental.cc)
+    target_sources(heif PRIVATE api/libheif/heif_experimental.h api/libheif/heif_experimental.cc)
 
     list(APPEND libheif_headers api/libheif/heif_experimental.h)