diff --git a/ffi.h b/ffi.h
index 8d5eac2..0b0c2f6 100644
--- a/ffi.h
+++ b/ffi.h
@@ -174,6 +174,9 @@ typedef struct _ffi_type
 /* of the library, but don't worry about that.  Besides,  */
 /* as a workaround, they can define FFI_BUILDING if they  */
 /* *know* they are going to link with the static library. */
+
+#define FFI_BUILDING
+
 #if defined _MSC_VER && !defined FFI_BUILDING
 #define FFI_EXTERN extern __declspec(dllimport)
 #else