diff --git a/onionr/communicator.py b/onionr/communicator.py
index bdc11256..ee0fed46 100755
--- a/onionr/communicator.py
+++ b/onionr/communicator.py
@@ -108,6 +108,8 @@ class OnionrCommunicate:
         logger.debug('BLOCKS: \n' + blocks)
         blockList = blocks.split('\n')
         for i in blockList:
+            if self._utils.hasBlock(i):
+                continue
             logger.debug('Exchanged block (blockList): ' + i)
             if not self._utils.validateHash(i):
                 # skip hash if it isn't valid
diff --git a/onionr/onionrutils.py b/onionr/onionrutils.py
index 1f0190f1..ec7517e2 100644
--- a/onionr/onionrutils.py
+++ b/onionr/onionrutils.py
@@ -18,7 +18,7 @@
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 '''
 # Misc functions that do not fit in the main api, but are useful
-import getpass, sys, requests, configparser, os, socket, gnupg, hashlib, logger
+import getpass, sys, requests, configparser, os, socket, gnupg, hashlib, logger, sqlite3
 if sys.version_info < (3, 6):
     try:
         import sha3
@@ -96,6 +96,22 @@ class OnionrUtils:
         dataHash = hasher.hexdigest()
         return dataHash
 
+    def hasBlock(self, hash):
+        '''detect if we have a block in the list or not'''
+        conn = sqlite3.connect(self._core.blockDB)
+        c = conn.cursor()
+        if not self.validateHash(hash):
+            raise Exception("Invalid hash")
+        for result in c.execute("SELECT COUNT() FROM hashes where hash='" + hash + "'"):
+            if result[0] >= 1:
+                conn.commit()
+                conn.close()
+                return True
+            else:
+                conn.commit()
+                conn.close()
+                return False
+
     def validateHash(self, data, length=64):
         '''Validate if a string is a valid hex formatted hash'''
         retVal = True