diff --git a/src/Reactor/LLVMReactor.cpp b/src/Reactor/LLVMReactor.cpp
index e2a82a0..a6c6bd3 100644
--- a/src/Reactor/LLVMReactor.cpp
+++ b/src/Reactor/LLVMReactor.cpp
@@ -27,6 +27,8 @@
 #undef max
 
 #if REACTOR_LLVM_VERSION < 7
+#error "LLVM 3 backend is deprecated, and will be removed shortly"
+
 	#include "llvm/Analysis/LoopPass.h"
 	#include "llvm/Constants.h"
 	#include "llvm/Function.h"