diff --git a/server.py b/server.py
index 3e697e9..8e8921d 100644
--- a/server.py
+++ b/server.py
@@ -3,12 +3,16 @@
 import string
 from http.server import HTTPServer, BaseHTTPRequestHandler
 from io import BytesIO
+import string
 import base64
 
 
 NULL_CHAR = chr(0)
 file = open('/dev/hidg0', 'rb+')
 
+alphabet_lower = set(string.ascii_lowercase)
+alphabet_upper = set(string.ascii_uppercase)
+
 colors = {
     "Z": "a",  # Black
     "B": "b",  # Blue
@@ -37,9 +41,9 @@ def release_keys():
 
 
 def printchar(c):
-    if c.islower():
+    if c in alphabet_lower:
         write_report(NULL_CHAR*2+chr(4 + ord(c) - ord('a'))+NULL_CHAR*5)
-    elif c.isupper():
+    elif c in alphabet_upper:
         write_report(chr(32)+NULL_CHAR+chr(4 + ord(c) - ord('A'))+NULL_CHAR*5)
     elif c.isdigit():
         write_report(NULL_CHAR*2+chr(0x1e + ((ord(c) - ord('0') - 1) % 10))+NULL_CHAR*5)