diff --git a/reactos/dll/3rdparty/libjpeg/CMakeLists.txt b/reactos/dll/3rdparty/libjpeg/CMakeLists.txt
index 10ef59a6708..516faba31fd 100644
--- a/reactos/dll/3rdparty/libjpeg/CMakeLists.txt
+++ b/reactos/dll/3rdparty/libjpeg/CMakeLists.txt
@@ -3,7 +3,8 @@ add_definitions(
     -DWIN32
     -D_WINDOWS
     -D_MBCS
-    -DJPEG_DLL)
+    -DJPEG_DLL
+    -Dmain=mainptr)
 
 include_directories(
     ${REACTOS_SOURCE_DIR}/include/reactos/libs/libjpeg