diff --git a/vyper/evm/assembler/core.py b/vyper/evm/assembler/core.py
index 5c553fd4d2..2fa8a96aa2 100644
--- a/vyper/evm/assembler/core.py
+++ b/vyper/evm/assembler/core.py
@@ -17,8 +17,13 @@
 from vyper.evm.opcodes import get_opcodes
 from vyper.exceptions import CompilerPanic
 
+# EVM opcode base values for PUSH, DUP, and SWAP instructions
+# These constants are used to calculate opcodes: OFFSET + instruction_number
+# PUSH0 = 0x5F, PUSH1 = 0x60, PUSH2 = 0x61, etc.
 PUSH_OFFSET = 0x5F
+# DUP1 = 0x80, DUP2 = 0x81, DUP3 = 0x82, etc.
 DUP_OFFSET = 0x7F
+# SWAP1 = 0x90, SWAP2 = 0x91, SWAP3 = 0x92, etc.
 SWAP_OFFSET = 0x8F