Index: ext/gd/libgd/gd.c
===================================================================
--- ext/gd/libgd/gd.c	(revision 286466)
+++ ext/gd/libgd/gd.c	(revision 287979)
@@ -591,7 +591,7 @@
 		if (im->transparent != -1) {
 			im->alpha[im->transparent] = gdAlphaOpaque;
 		}
-		if (color > -1 && color<im->colorsTotal && color<=gdMaxColors) {
+		if (color > -1 && color < im->colorsTotal && color < gdMaxColors) {
 			im->alpha[color] = gdAlphaTransparent;
 		} else {
 			return;