define RULE_NOSCREEN -1

client.c

@@ -363,7 +363,7 @@ client_manage(Window w, XWindowAttributes *wa, awesome_config *awesomeconf)
 
     /* rearrange to display new window */
     arrange(awesomeconf);
-    if(newscreen != -1)
+    if(newscreen != RULE_NOSCREEN)
         arrange(&awesomeconf[newscreen - awesomeconf->screen]);
 }
 

config.c

@@ -283,7 +283,7 @@ parse_config(const char *confpatharg, awesome_config *awesomeconf)
         CFG_STR((char *) "name", (char *) "", CFGF_NONE),
         CFG_STR((char *) "tags", (char *) "", CFGF_NONE),
         CFG_BOOL((char *) "float", cfg_false, CFGF_NONE),
-        CFG_INT((char *) "screen", -1, CFGF_NONE),
+        CFG_INT((char *) "screen", RULE_NOSCREEN, CFGF_NONE),
         CFG_END()
     };
     static cfg_opt_t rules_opts[] =

tag.c

@@ -58,7 +58,7 @@ applyrules(Client *c, awesome_config *awesomeconf)
                 }
                 else
                     c->tags[j] = False;
-            if(r->screen != -1 && r->screen != awesomeconf->screen)
+            if(r->screen != RULE_NOSCREEN && r->screen != awesomeconf->screen)
             {
                 screen = r->screen;
                 move_client_to_screen(c, &awesomeconf[r->screen - awesomeconf->screen], True);

tag.h

@@ -24,6 +24,8 @@
 
 #include "client.h"
 
+#define RULE_NOSCREEN                                     -1
+
 /** Check if a client is tiled */
 #define IS_TILED(client, screen, tags, ntags)            (client && !client->isfloating && isvisible(client, screen, tags, ntags))