diff --git a/src/gui_w32.c b/src/gui_w32.c
index cbfe662..7bdbf41 100644
--- a/src/gui_w32.c
+++ b/src/gui_w32.c
@@ -1712,7 +1712,7 @@
     /*
      * Try to look up a system colour.
      */
-    for (i = 0; i < ARRAY_LENGTH(sys_table); i++)
+    for (i = 0; i < (int)ARRAY_LENGTH(sys_table); i++)
 	if (STRICMP(name, sys_table[i].name) == 0)
 	    return GetSysColor(sys_table[i].color);