diff --git a/src/cli.py b/src/cli.py
--- a/src/cli.py
+++ b/src/cli.py
@@ -12,7 +12,7 @@ def run():
 	buildSplitParser(subparsers.add_parser("split"))
 	buildJoinParser(subparsers.add_parser("join"))
 
-	parser.set_defaults(func=lambda: parser.error("missing command"))
+	parser.set_defaults(func=lambda _: parser.error("missing command"))
 
 	args=parser.parse_args()
 	args.func(args)
@@ -45,14 +45,20 @@ def buildJoinParser(parser):
 def _generate(args):
 	encoding=getEncoding(args) or "b32"
 
-	shares=generate(args.secret,args.k,args.n,encoding)
-	for s in shares:
-		print(s)
+	try:
+		shares=generate(args.secret,args.k,args.n,encoding)
+		for s in shares:
+			print(s)
+	except ValueError as e:
+		print("operation failed: ",e)
 
 
 def _reconstruct(args):
 	encoding=getEncoding(args)
-	print(reconstruct(*args.share,encoding=encoding,raw=args.raw))
+	try:
+		print(reconstruct(*args.share,encoding=encoding,raw=args.raw))
+	except ValueError as e:
+		print("operation failed: ",e)
 
 
 def getEncoding(args):