diff --git a/lib/Immediate/Immediate.cpp b/lib/Immediate/Immediate.cpp
index 9ddf9511fe332..47601bf1ab3ea 100644
--- a/lib/Immediate/Immediate.cpp
+++ b/lib/Immediate/Immediate.cpp
@@ -30,6 +30,7 @@
 #include "swift/Basic/LLVM.h"
 #include "swift/Frontend/Frontend.h"
 #include "swift/IRGen/IRGenPublic.h"
+#include "swift/Runtime/Config.h"
 #include "swift/SILOptimizer/PassManager/Passes.h"
 #include "swift/Subsystems.h"
 #include "llvm/ADT/SmallString.h"