diff --git a/rtengine/dcraw.h b/rtengine/dcraw.h
index 0a3316d63..2c47ee7e5 100644
--- a/rtengine/dcraw.h
+++ b/rtengine/dcraw.h
@@ -350,7 +350,7 @@ private:
 
    DCraw *parent;
    short ℴ
-   IMFILE *&ifp;
+   IMFILE* const ifp;
    UINT64 bitbuf;
    int vbits;
 };