diff --git a/web3/confutils_defs.nim b/web3/confutils_defs.nim
new file mode 100644
index 0000000..2f4fc50
--- /dev/null
+++ b/web3/confutils_defs.nim
@@ -0,0 +1,17 @@
+import
+  ethtypes
+
+func parseCmdArg*(T: type Address, input: TaintedString): T
+                 {.raises: [ValueError, Defect].} =
+  fromHex(T, string input)
+
+func completeCmdArg*(T: type Address, input: TaintedString): seq[string] =
+  return @[]
+
+func parseCmdArg*(T: type BlockHash, input: TaintedString): T
+                 {.raises: [ValueError, Defect].} =
+  fromHex(T, string input)
+
+func completeCmdArg*(T: type BlockHash, input: TaintedString): seq[string] =
+  return @[]
+