diff --git a/goodchain/src/helpers/TaskHelper.py b/goodchain/src/helpers/TaskHelper.py
index bd54810..105f0b1 100644
--- a/goodchain/src/helpers/TaskHelper.py
+++ b/goodchain/src/helpers/TaskHelper.py
@@ -50,6 +50,18 @@ def transaction(self):
     return new_tx
 
 def createBlock(self):
+        # add last block if its available
+    try:
+        lastBlock = utilityHelper.loadFile("../data/ledger.dat")
+    except:
+        lastBlock = None
+    if lastBlock != None:
+        lastBlock = lastBlock[-1]
+    
+    if lastBlock != None and time.time() - lastBlock.date < 180:
+        print("You can only mine a block every 3 minutes")
+        return False
+    
     transactions = Tx()
     transactions = utilityHelper.loadFile("../data/transaction_pool.dat")
     if len(transactions) < 5:
@@ -117,14 +129,6 @@ def createBlock(self):
         print("You need atleast 1 transaction from another user")
         return False
     
-    # add last block if its available
-    try:
-        lastBlock = utilityHelper.loadFileLine("../data/ledger.dat")
-    except:
-        lastBlock = None
-    if lastBlock != None:
-        lastBlock = lastBlock[0]
-    
     block = TxBlock(lastBlock)
 
     # create block