diff --git a/project.xml b/project.xml
index 86036f0d7..25ee2d51b 100644
--- a/project.xml
+++ b/project.xml
@@ -234,6 +234,12 @@
 	<haxedef name="HXCPP_CHECK_POINTER" />
 	<haxedef name="HXCPP_STACK_LINE" />
 	<haxedef name="HXCPP_CATCH_SEGV" />
+	<haxedef name="HXCPP_GC_GENERATIONAL" />
+	<haxedef name="HXCPP_GC_DYNAMIC_SIZE" />
+	<haxedef name="HXCPP_CPP17" />
+	<haxedef name="HXCPP_GC_BIG_BLOCKS" />
+	<haxedef name="HXCPP_ALIGN_ALLOC" />
+	<haxedef name="HXCPP_FAST_LINK"/>
 
 	<haxedef name="hscriptPos" /> <!-- for logging -->