diff --git a/CImg.h b/CImg.h
index b409bce94e31007498e37d79b2b3bbe0a497fa73..0ebeb0329c6fdc0d49e6fdf5c531a1990124932c 100644
--- a/CImg.h
+++ b/CImg.h
@@ -20559,7 +20559,7 @@ namespace cimg_library_suffixed {
           dy = (unsigned int)mp.opcode[8],
           dz = (unsigned int)mp.opcode[9],
           dc = (unsigned int)mp.opcode[10];
-        const bool boundary_conditions = (bool)_mp_arg(11);
+        const unsigned int boundary_conditions = (unsigned int)_mp_arg(11);
         unsigned int ind = (unsigned int)mp.opcode[2];
         if (ind!=~0U) ind = (unsigned int)cimg::mod((int)_mp_arg(2),mp.listin.width());
         const CImg<T> &img = ind==~0U?mp.imgin:mp.listin[ind];