--- /local/app/leptonlib-1.56/src/colormap.c	2008-05-13 18:34:39.000000000 +0400
+++ src/colormap.c	2008-05-15 12:55:29.000000000 +0400
@@ -476,7 +476,7 @@
 
     if (!cmap)
         return ERROR_INT("cmap not defined", procName, 1);
-    if (index >= cmap->n)
+    if (index < 0 || index >= cmap->n)
         return ERROR_INT("index out of bounds", procName, 1);
 
     cta = (RGBA_QUAD *)cmap->array;