diff --git a/src/client.py b/src/client.py
--- a/src/client.py
+++ b/src/client.py
@@ -58,15 +58,18 @@ def negotiate(incoming,outcoming):
 def sendData(outcoming,blocksToTransfer):
 	print(blocksToTransfer)
 	dataFile=open(filename,mode="rb")
+	i1=-1
 
-	for i in blocksToTransfer:
-		jsonData={"command":"send", "index":i, "dataType":"data"}
-		dataFile.seek(i*HashTree.BLOCK_SIZE)
+	for i2 in blocksToTransfer:
+		jsonData={"command":"send", "index":i2, "dataType":"data"}
+		if i1+1!=i2:
+			dataFile.seek(i2*HashTree.BLOCK_SIZE)
 		binData=dataFile.read(HashTree.BLOCK_SIZE)
 
-		print("block #{0}: {1}...{2}".format(i,binData[:5],binData[-5:]))
+		print("block #{0}: {1}...{2}".format(i2,binData[:5],binData[-5:]))
 
 		outcoming.put((jsonData,binData),timeout=2)
+		i1=i2
 
 	jsonData={"command":"end"}
 	outcoming.put((jsonData,b""),timeout=2)