diff --git a/onionr/api.py b/onionr/api.py
index 90a3b83e..34c320d9 100755
--- a/onionr/api.py
+++ b/onionr/api.py
@@ -24,7 +24,7 @@ from gevent.wsgi import WSGIServer
 import sys, random, threading, hmac, hashlib, base64, time, math, os, json
 from core import Core
 from onionrblockapi import Block
-import onionrutils, onionrcrypto, blockimporter, onionrevents as events, logger, config
+import onionrutils, onionrexceptions, onionrcrypto, blockimporter, onionrevents as events, logger, config
 
 class API:
     '''
@@ -119,9 +119,7 @@ class API:
             '''
                 Simply define the request as not having yet failed, before every request.
             '''
-
             self.requestFailed = False
-
             return
 
         @app.after_request
@@ -397,10 +395,14 @@ class API:
                 pass
             else:
                 if sys.getsizeof(data) < 100000000:
-                    if blockimporter.importBlockFromData(data, self._core):
-                        resp = 'success'
-                    else:
-                        logger.warn('Error encountered importing uploaded block')
+                    try:
+                        if blockimporter.importBlockFromData(data, self._core):
+                            resp = 'success'
+                        else:
+                            logger.warn('Error encountered importing uploaded block')
+                    except onionrexceptions.BlacklistedBlock:
+                        logger.debug('uploaded block is blacklisted')
+                        pass
 
             resp = Response(resp)
             return resp
diff --git a/onionr/blockimporter.py b/onionr/blockimporter.py
index a2695093..f5698d00 100644
--- a/onionr/blockimporter.py
+++ b/onionr/blockimporter.py
@@ -20,6 +20,12 @@
 import core, onionrexceptions, logger
 def importBlockFromData(content, coreInst):
     retData = False
+
+    dataHash = coreInst._getSha3Hash(content)
+
+    if coreInst._blacklist.inBlacklist(dataHash):
+        raise onionrexceptions.BlacklistedBlock('%s is a blacklisted block' % (dataHash,))
+
     if not isinstance(coreInst, core.Core):
         raise Exception("coreInst must be an Onionr core instance")
 
diff --git a/onionr/core.py b/onionr/core.py
index 440f31e0..8f517e82 100644
--- a/onionr/core.py
+++ b/onionr/core.py
@@ -133,7 +133,6 @@ class Core:
             for i in c.execute("SELECT * FROM adders where address = '" + address + "';"):
                 try:
                     if i[0] == address:
-                        logger.warn('Not adding existing address')
                         conn.close()
                         return False
                 except ValueError:
@@ -311,16 +310,24 @@ class Core:
 
         return data
 
-    def setData(self, data):
-        '''
-            Set the data assciated with a hash
-        '''
-        data = data
+    def _getSha3Hash(self, data):
         hasher = hashlib.sha3_256()
         if not type(data) is bytes:
             data = data.encode()
         hasher.update(data)
         dataHash = hasher.hexdigest()
+        return dataHash
+
+    def setData(self, data):
+        '''
+            Set the data assciated with a hash
+        '''
+        data = data
+        if not type(data) is bytes:
+            data = data.encode()
+            
+        dataHash = self._getSha3Hash(data)
+
         if type(dataHash) is bytes:
             dataHash = dataHash.decode()
         blockFileName = self.blockDataLocation + dataHash + '.dat'
diff --git a/onionr/onionrexceptions.py b/onionr/onionrexceptions.py
index 2817d419..7b0de6c7 100644
--- a/onionr/onionrexceptions.py
+++ b/onionr/onionrexceptions.py
@@ -38,6 +38,9 @@ class InvalidPubkey(Exception):
 class InvalidMetadata(Exception):
     pass
 
+class BlacklistedBlock(Exception):
+    pass
+
 class InvalidHexHash(Exception):
     '''When a string is not a valid hex string of appropriate length for a hash value'''
     pass
diff --git a/onionr/onionrpeers.py b/onionr/onionrpeers.py
index 21697033..2762277c 100644
--- a/onionr/onionrpeers.py
+++ b/onionr/onionrpeers.py
@@ -72,7 +72,7 @@ def getScoreSortedPeerList(coreInst):
     return peerList
 
 def peerCleanup(coreInst):
-    '''Removes peers who have been offline too long'''
+    '''Removes peers who have been offline too long or score too low'''
     if not type(coreInst is core.Core):
         raise TypeError('coreInst must be instance of core.Core')