diff --git a/nimbus/vm/interpreter/opcodes_impl.nim b/nimbus/vm/interpreter/opcodes_impl.nim
index 3a2daa04f..73432a761 100644
--- a/nimbus/vm/interpreter/opcodes_impl.nim
+++ b/nimbus/vm/interpreter/opcodes_impl.nim
@@ -253,26 +253,19 @@ op callValue, inline = true:
 
 op callDataLoad, inline = false, startPos:
   ## 0x35, Get input data of current environment
-  let dataPos = startPos.cleanMemRef
-  if dataPos >= computation.msg.data.len:
+  let start = startPos.cleanMemRef
+  if start >= computation.msg.data.len:
     push: 0
     return
 
-  let dataEndPosition = dataPos + 31
+  # If the data does not take 32 bytes, pad with zeros
+  let endRange = min(computation.msg.data.len - 1, start + 31)
+  let presentBytes = endRange - start
+  # We rely on value being initialized with 0 by default
+  var value: array[32, byte]
+  value[0 .. presentBytes] = computation.msg.data.toOpenArray(start, endRange)
 
-  if dataEndPosition < computation.msg.data.len:
-    computation.stack.push(computation.msg.data[dataPos .. dataEndPosition])
-  else:
-    var bytes: array[32, byte]
-    var presentBytes = min(computation.msg.data.len - dataPos, 32)
-
-    if presentBytes > 0:
-      copyMem(addr bytes[0], addr computation.msg.data[dataPos], presentBytes)
-    else:
-      presentBytes = 0
-
-    for i in presentBytes ..< 32: bytes[i] = 0
-    computation.stack.push(bytes)
+  push: value
 
 op callDataSize, inline = true:
   ## 0x36, Get size of input data in current environment.
diff --git a/tests/all_tests.nim b/tests/all_tests.nim
index da8335a17..82d3edb72 100644
--- a/tests/all_tests.nim
+++ b/tests/all_tests.nim
@@ -21,5 +21,6 @@ import  ./test_code_stream,
         ./test_op_env,
         ./test_op_memory,
         ./test_op_misc,
+        ./test_op_custom,
         ./test_state_db
 
diff --git a/tests/test_op_custom.nim b/tests/test_op_custom.nim
index 4c78a9f44..2eb7540ea 100644
--- a/tests/test_op_custom.nim
+++ b/tests/test_op_custom.nim
@@ -6,16 +6,6 @@ import
 suite "Custom Opcodes Test":
   let (blockNumber, chainDB) = initDatabase()
 
-  var acc: EthAddress
-  hexToByteArray("0xc669eaad75042be84daaf9b461b0e868b9ac1871", acc)
-  var
-    parent = chainDB.getBlockHeader(blockNumber - 1)
-    stateDB = newAccountStateDB(chainDB.db, parent.stateRoot, false)
-
-  stateDB.setBalance(acc, 1000.u256)
-  parent.stateRoot = stateDB.rootHash
-  chainDB.setHead(parent, true)
-
   assembler: # CALLDATASIZE OP
     title: "CALLDATASIZE_1"
     data:
@@ -81,6 +71,15 @@ suite "Custom Opcodes Test":
       CallDataLoad
     success: false
 
+  assembler: # CALLDATALOAD OP
+    title: "CALLDATALOAD_7"
+    data:
+      "0x00000000000000000000000000000000000000000000000000000000000000A1"
+      "0x00000000000000000000000000000000000000000000000000000000000000B1"
+    code:
+      Push1 "0x40"
+      CallDataLoad
+    stack: "0x00"
 
   assembler: # CALLDATACOPY OP
     title: "CALLDATACOPY_1"
@@ -185,7 +184,7 @@ suite "Custom Opcodes Test":
     code:
       Address
       Balance
-    stack: "0x00000000000000000000000000000000000000000000000000000000000003E8"
+    stack: "0x000000000000000000000000000000000000000000000000cff56a1b273a8000"
 
   assembler: # ORIGIN OP
     title: "ORIGIN_1"
@@ -241,42 +240,40 @@ suite "Custom Opcodes Test":
     stack: "0x02"
     memory: "0x0000000000000000000000000000000000000000000000000000000000000201"
 
-#[
   assembler: # BLOCKHASH OP
     title: "BLOCKHASH_1"
     code:
-      Push1 "0x01"
+      Push2 "0xb864" # 47204, parent header number
       Blockhash
-    stack: "0xC89EFDAA54C0F20C7ADF612882DF0950F5A951637E0307CDCB4C672F298B8BC6"
-]#
+    stack: "0xa85842a20755232169db76c5bd4ad4672c1551fca4b07d0bd139cd0e6fef684d"
 
-  # current coinbase or parent coinbase?
+  # current block coinbase/miner
   assembler: # COINBASE OP
     title: "COINBASE_1"
     code:
       Coinbase
-    stack: "0x000000000000000000000000c0ede9a639d107851462c15f2fb729c7c61bbf62"
+    stack: "0x000000000000000000000000bb7b8287f3f0a933474a79eae42cbca977791171"
 
-  # current timestamp or parent timestamp?
+  # current block timestamp
   assembler: # TIMESTAMP OP
     title: "TIMESTAMP_1"
     code:
       TimeStamp
-    stack: "0x0000000000000000000000000000000000000000000000000000000055c46bb3"
+    stack: "0x0000000000000000000000000000000000000000000000000000000055c46bba"
 
-  # it should be current block number
+  # current block number
   assembler: # NUMBER OP
     title: "NUMBER_1"
     code:
       Number
     stack: "0x000000000000000000000000000000000000000000000000000000000000b865"
 
-  # current difficulty or parent dificulty?
+  # current difficulty
   assembler: # DIFFICULTY OP
     title: "DIFFICULTY_1"
     code:
       Difficulty
-    stack: "0x0000000000000000000000000000000000000000000000000000015451e94505"
+    stack: "0x000000000000000000000000000000000000000000000000000001547c73822d"
 
   # ??
   assembler: # GASPRICE OP
@@ -297,7 +294,7 @@ suite "Custom Opcodes Test":
     title: "GASLIMIT_1"
     code:
       GasLimit
-    stack: "0x000000000000000000000000000000000000000000000000000000000000a271"
+    stack: "0x000000000000000000000000000000000000000000000000000000000000a298"
 
   assembler: # INVALID OP
     title: "INVALID_1"