diff --git a/polymer/eduke32/Makefile.common b/polymer/eduke32/Makefile.common
index 72dc3f13e..938d4297f 100644
--- a/polymer/eduke32/Makefile.common
+++ b/polymer/eduke32/Makefile.common
@@ -243,6 +243,10 @@ ifneq ($(LUNATIC),0)
     # FIXME: Lunatic builds with LTO don't start up properly as the required
     # symbol names are apparently not exported.
     override LTO=0
+
+    ifneq ($(LUNATIC),0)
+        $(error "Lunatic C++ build not supported")
+    endif
 endif
 
 ifndef LTO