diff --git a/nemesis-generator/generator/__main__.py b/nemesis-generator/generator/__main__.py
index 5d743c8f..6ebe98f7 100644
--- a/nemesis-generator/generator/__main__.py
+++ b/nemesis-generator/generator/__main__.py
@@ -26,7 +26,6 @@ def attach_signature(payload, signature):
 	writer.write_bytes(payload[:ENTITY_HEADER_SIZE])
 	writer.write_int(Signature.SIZE, 4)
 	writer.write_bytes(signature.bytes)
-
 	writer.write_bytes(payload[ENTITY_HEADER_SIZE:])
 	return writer.buffer
 
@@ -49,6 +48,8 @@ def __init__(self, input_file):
 			self.generation_hash = Hash256(nemesis_config['generation_hash'])
 			self.accounts = nemesis_config['accounts']
 
+			self.previous_block_hash = Hash256.zero()
+
 		self.unsigned_transaction_payloads = []
 		self.signed_transaction_payloads = []
 		self.signed_block_header = None
@@ -97,18 +98,18 @@ def prepare_block(self):
 		writer.write_int(0xFFFFFFFF, 4)  # type
 		self._write_entity_header(writer)
 
-		writer.write_int(Hash256.SIZE + 4, 4)
+		writer.write_int(Hash256.SIZE + 4, 4)  # needed to deserialize the previous block hash object
 		writer.write_int(Hash256.SIZE, 4)
-		writer.write_bytes(self.generation_hash.bytes)
+		writer.write_bytes(self.previous_block_hash.bytes)
 
 		writer.write_int(1, 8)  # height
 
-		writer.write_int(len(self.unsigned_transaction_payloads), 4)  # transactions count
+		writer.write_int(len(self.signed_transaction_payloads), 4)  # transactions count
 
 		unsigned_block_header = writer.buffer[:]
 
-		for unsigned_transaction_payload in self.unsigned_transaction_payloads:
-			writer.write_bytes(unsigned_transaction_payload)
+		for signed_transaction_payload in self.signed_transaction_payloads:
+			writer.write_bytes(signed_transaction_payload)
 
 		unsigned_block = writer.buffer
 		signature = self.signer_key_pair.sign(unsigned_block)
diff --git a/nemesis-generator/requirements.txt b/nemesis-generator/requirements.txt
index de524d20..909d552c 100644
--- a/nemesis-generator/requirements.txt
+++ b/nemesis-generator/requirements.txt
@@ -1,3 +1,3 @@
-PyYAML==6.0
-symbol-sdk-python==3.0.7
+PyYAML==6.0.2
+symbol-sdk-python==3.2.3
 zenlog==1.1