diff -up ./src/gdxpm.c.color_c_null_pointer ./src/gdxpm.c
--- ./src/gdxpm.c.color_c_null_pointer	2013-06-25 11:58:23.000000000 +0200
+++ ./src/gdxpm.c	2014-07-16 16:43:44.000000000 +0200
@@ -62,6 +62,13 @@ BGD_DECLARE(gdImagePtr) gdImageCreateFro
 
 	for(i = 0; i < number; i++) {
 		char *c_color = image.colorTable[i].c_color;
+		if (!c_color)
+		{
+			/* unsupported color key or color key not defined */
+			gdImageDestroy(im);
+			im = 0;
+			goto done;
+		}
 		if(strcmp(c_color, "None") == 0) {
 			colors[i] = gdImageGetTransparent(im);
 			if(colors[i] == -1) colors[i] = gdImageColorAllocate(im, 0, 0, 0);
diff -up ./x.color_c_null_pointer ./x