diff --git a/rtengine/clutstore.cc b/rtengine/clutstore.cc
index ea3a2a7fc..9d0cea35a 100644
--- a/rtengine/clutstore.cc
+++ b/rtengine/clutstore.cc
@@ -56,7 +56,7 @@ bool loadFile(
             img_src.convertColorSpace(img_float.get(), icm, curr_wb);
         }
 
-        AlignedBuffer<std::uint16_t> image(fw * fh * 4 + 1);
+        AlignedBuffer<std::uint16_t> image(fw * fh * 4 + 4);
 
         std::size_t index = 0;