From f0a3a23195b3279c081d10dd9dfbf0831166bdde Mon Sep 17 00:00:00 2001
From: lightclient <14004106+lightclient@users.noreply.github.com>
Date: Sat, 8 May 2021 22:54:31 -0600
Subject: [PATCH] start with default base fee on fork block (#3556)

---
 EIPS/eip-1559.md | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/EIPS/eip-1559.md b/EIPS/eip-1559.md
index 20058965..3abbb660 100644
--- a/EIPS/eip-1559.md
+++ b/EIPS/eip-1559.md
@@ -139,7 +139,7 @@ class Block:
 	extra_data: bytes = bytes()
 	proof_of_work: int = 0
 	nonce: int = 0
-	base_fee_per_gas: int = 0 # default to 1,000,000,000 for blocks before INITIAL_FORK_BLOCK_NUMBER
+	base_fee_per_gas: int = 0
 
 @dataclass
 class Account:
@@ -149,6 +149,7 @@ class Account:
 	storage_root: int = 0
 	code_hash: int = 0
 
+INITIAL_BASE_FEE = 1000000000
 INITIAL_FORK_BLOCK_NUMBER = 10 # TBD
 BASE_FEE_MAX_CHANGE_DENOMINATOR = 8
 ELASTICITY_MULTIPLIER = 2
@@ -157,7 +158,7 @@ class World(ABC):
 	def validate_block(self, block: Block) -> None:
 		parent_gas_target = self.parent(block).gas_limit // ELASTICITY_MULTIPLIER
 
-		# On the fork block, don't account for the ELASTICITY_MULTIPLIER to avoid
+		# on the fork block, don't account for the ELASTICITY_MULTIPLIER to avoid
 		# unduly halving the gas target.
 		if INITIAL_FORK_BLOCK_NUMBER == block.number:
 			parent_gas_target = self.parent(block).gas_limit 
@@ -175,7 +176,9 @@ class World(ABC):
 		assert gas_target >= parent_gas_target - parent_gas_target // 1024, 'invalid block: gas target decreased too much'
 
 		# check if the base fee is correct
-		if parent_gas_used == parent_gas_target:
+		if INITIAL_FORK_BLOCK_NUMBER == block.number:
+			expected_base_fee_per_gas = INITIAL_BASE_FEE
+		elif parent_gas_used == parent_gas_target:
 			expected_base_fee_per_gas = parent_base_fee_per_gas
 		elif parent_gas_used > parent_gas_target:
 			gas_used_delta = parent_gas_used - parent_gas_target