diff --git a/src/bin/keygen.rs b/src/bin/keygen.rs
index 9fe12144f3..1c2326d775 100644
--- a/src/bin/keygen.rs
+++ b/src/bin/keygen.rs
@@ -21,6 +21,7 @@ fn main() -> Result<(), Box<error::Error>> {
                 .long("outfile")
                 .value_name("PATH")
                 .takes_value(true)
+                .required(true)
                 .help("path to generated file"),
         ).get_matches();