diff --git a/wmifs/wmifs-mask.xbm b/wmifs/wmifs-mask.xbm
index 8599f49..9b0c27e 100644
--- a/wmifs/wmifs-mask.xbm
+++ b/wmifs/wmifs-mask.xbm
@@ -1,6 +1,6 @@
 #define wmifs_mask_width 64
 #define wmifs_mask_height 64
-static char wmifs_mask_bits[] = {
+static unsigned char wmifs_mask_bits[] = {
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
diff --git a/wmifs/wmifs.c b/wmifs/wmifs.c
index 9c56f63..0bb0e89 100644
--- a/wmifs/wmifs.c
+++ b/wmifs/wmifs.c
@@ -442,7 +442,7 @@ void wmifs_routine(int argc, char **argv)
 
 	parse_rcfile("/etc/wmifsrc.fixed", wmifs_keys);
 
-	openXwindow(argc, argv, wmifs_master_xpm, wmifs_mask_bits, wmifs_mask_width, wmifs_mask_height);
+	openXwindow(argc, argv, wmifs_master_xpm, (char*)wmifs_mask_bits, wmifs_mask_width, wmifs_mask_height);
 
 	/* > Button */
 	AddMouseRegion(0, 5, 5, 35, 15);