diff --git a/src/common.c b/src/common.c
index 9b32f84..22b6d38 100644
--- a/src/common.c
+++ b/src/common.c
@@ -82,6 +82,17 @@ int setgroups(int count, int *groups)
 }
 #endif
 
+
+void
+check_superuser(void (*usage_fn)(void))
+{
+	if (geteuid() != 0) {
+		warnx("Run as root and you'll be happy.\n");
+		usage_fn();
+		/* NOTREACHED */
+	}
+}
+
 int 
 open_dns(int localport, in_addr_t listen_ip) 
 {
diff --git a/src/common.h b/src/common.h
index edc8e82..06d57db 100644
--- a/src/common.h
+++ b/src/common.h
@@ -58,6 +58,7 @@ struct query {
 	int fromlen;
 };
 
+void check_superuser(void (*usage_fn)(void));
 int open_dns(int, in_addr_t);
 void close_dns(int);
 
diff --git a/src/iodine.c b/src/iodine.c
index 76d1e36..67a9bff 100644
--- a/src/iodine.c
+++ b/src/iodine.c
@@ -945,11 +945,7 @@ main(int argc, char **argv)
 		}
 	}
 	
-	if (geteuid() != 0) {
-		warnx("Run as root and you'll be happy.\n");
-		usage();
-		/* NOTREACHED */
-	}
+	check_superuser(usage);
 
 	argc -= optind;
 	argv += optind;
diff --git a/src/iodined.c b/src/iodined.c
index a1dc298..3295d44 100644
--- a/src/iodined.c
+++ b/src/iodined.c
@@ -1002,10 +1002,7 @@ main(int argc, char **argv)
 	argc -= optind;
 	argv += optind;
 
-	if (geteuid() != 0) {
-		warnx("Run as root and you'll be happy.\n");
-		usage();
-	}
+	check_superuser(usage);
 
 	if (argc != 2) 
 		usage();