diff --git a/scripts/install b/scripts/install
index 4c51b4a..0588a39 100644
--- a/scripts/install
+++ b/scripts/install
@@ -11,8 +11,8 @@ exit 1
 fi
 
 # Generate random DES key & password
-deskey=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d '[A-Za-z0-9]' | sed -n 's/\(.\{24\}\).*/\1/p')
-db_pwd=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d '[A-Za-z0-9]' | sed -n 's/\(.\{24\}\).*/\1/p')
+deskey=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d 'A-Za-z0-9' | sed -n 's/\(.\{24\}\).*/\1/p')
+db_pwd=$(dd if=/dev/urandom bs=1 count=200 2> /dev/null | tr -c -d 'A-Za-z0-9' | sed -n 's/\(.\{24\}\).*/\1/p')
 
 # Use 'ttrss' as database name and user
 db_user=ttrss