diff --git a/src/gui_xmebw.c b/src/gui_xmebw.c
index 2c66db1..3387fbe 100644
--- a/src/gui_xmebw.c
+++ b/src/gui_xmebw.c
@@ -455,7 +455,7 @@
     attr.valuemask = XpmColorSymbols | XpmCloseness | XpmColorKey;
     attr.closeness = 65535;	// accuracy isn't crucial
     attr.colorsymbols = color;
-    attr.numsymbols = sizeof(color) / sizeof(color[0]);
+    attr.numsymbols = ARRAY_LENGTH(color);
     attr.color_key = XPM_MONO;
     status = XpmCreatePixmapFromData(dpy, root, data, &pix, &mask, &attr);