diff --git a/src/main.c b/src/main.c
index 1ef007e..2cc3350 100644
--- a/src/main.c
+++ b/src/main.c
@@ -85,10 +85,8 @@ static struct option long_options[] = {
 static void usage(const char *prog)
 {
     fprintf(stderr, "Usage: %s [option]\n"
-            "      -g, --group=string       Set a group for the device(Any printable character except\n"
-            "                               space is allowed, with a maximum of 16 characters)\n"
-            "      -I, --id=string          Set an ID for the device(Any printable character except\n"
-            "                               space is allowed, with a maximum of 32 characters)\n"
+            "      -g, --group=string       Set a group for the device(max 16 chars, no spaces allowed)\n"
+            "      -I, --id=string          Set an ID for the device(max 32 chars, no spaces allowed)\n"
             "      -h, --host=string        Server's host or ipaddr(Default is localhost)\n"
             "      -p, --port=number        Server port(Default is 5912)\n"
             "      -d, --description=string Add a description to the device(Maximum 126 bytes)\n"
diff --git a/src/utils.c b/src/utils.c
index 029cc9c..9b29f40 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -52,14 +52,7 @@ bool valid_id(const char *id, size_t limit)
 {
     if (strlen(id) > limit)
         return false;
-
-    while (*id) {
-        if (!isprint(*id) || *id == ' ')
-            return false;
-        id++;
-    }
-
-    return true;
+    return !strchr(id, ' ');
 }
 
 /* reference from https://tools.ietf.org/html/rfc4648#section-4 */