diff --git a/panda/src/pnmimagetypes/pnmFileTypeTGA.h b/panda/src/pnmimagetypes/pnmFileTypeTGA.h
index 8e48baf757..2062dd618f 100644
--- a/panda/src/pnmimagetypes/pnmFileTypeTGA.h
+++ b/panda/src/pnmimagetypes/pnmFileTypeTGA.h
@@ -33,7 +33,7 @@ struct ImageHeader;
 
 
 /* Max number of colors allowed for colormapped output. */
-#define TGA_MAXCOLORS 256
+#define TGA_MAXCOLORS 257
 
 ////////////////////////////////////////////////////////////////////
 //       Class : PNMFileTypeTGA