diff --git a/magick/effect.c b/magick/effect.c
index 77b89a7..67a8b90 100644
--- a/magick/effect.c
+++ b/magick/effect.c
@@ -4625,7 +4625,7 @@
                   k++;
                 }
             }
-            j+=image->columns+width;
+            j+=(ssize_t) (image->columns+width);
           }
           if (gamma != 0.0)
             {