diff --git a/CMakeLists.txt b/CMakeLists.txt
index b0cc72db51..59ef0db0b4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -61,8 +61,13 @@ endif()
 option(AVIF_LOCAL_JPEG "Build jpeg by providing your own copy inside the ext subdir." OFF)
 if(AVIF_LOCAL_JPEG)
     add_subdirectory(ext/libjpeg)
-    set(JPEG_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ext/libjpeg" PARENT_SCOPE)
-    set(JPEG_LIBRARY jpeg PARENT_SCOPE)
+    if("${CMAKE_SOURCE_DIR}" STREQUAL  "${CMAKE_CURRENT_SOURCE_DIR}")
+        set(JPEG_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ext/libjpeg")
+        set(JPEG_LIBRARY jpeg)
+    else()
+        set(JPEG_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/ext/libjpeg" PARENT_SCOPE)
+        set(JPEG_LIBRARY jpeg PARENT_SCOPE)
+    endif()
 endif()
 # ---------------------------------------------------------------------------------------