diff --git a/README.md b/README.md
index 80cb8ee..26f96f9 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,38 @@
-# crawler-full-node
\ No newline at end of file
+# crawler-full-node
+
+### requirements
+```
+php-7.4
+php-curl
+php-mbstring
+php-mysql
+php-bcmath
+```
+
+#### database
+
+https://github.com/kvazar-network/database
+
+#### kevacoind
+
+https://github.com/kevacoin-project/kevacoin
+
+#### kevacoin.conf
+
+```
+rpcuser=user
+rpcpassword=password
+rpcport=9992
+server=1
+addressindex=1
+txindex=1
+rpcallowip=127.0.0.1
+whitelist=127.0.0.1
+```
+
+#### crontab
+```
+@reboot /path-to/kevacoind > /dev/null 2>&1
+* * * * * /path-to/kevacoind > /dev/null 2>&1
+* * * * * /path-to/php /path-to/crawler-full-node/crawler.php > /dev/null 2>&1
+```
diff --git a/crawler.php b/crawler.php
index 332635b..3780577 100644
--- a/crawler.php
+++ b/crawler.php
@@ -19,7 +19,7 @@ if (false !== sem_acquire($semaphore, 1)) {
   $blockLast  = $db->getLastBlock();
   $blockTotal = $kevaCoin->getblockcount();
 
-  if (!$blockTotal) {
+  if (false === $blockTotal) {
     echo "API connection error.\n";
     exit;
   }