diff --git a/src/args.rs b/src/args.rs
index 54b37d0..8a60156 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -37,7 +37,7 @@ pub fn get_matches_for(args: Vec<&str>) -> Result<ArgMatches<'static>> {
     return build().get_matches_from_safe(args);
 }
 
-pub fn get_verbose(m: ArgMatches) -> u64 {
+pub fn get_verbose(m: &ArgMatches) -> u64 {
     let sub = m.subcommand_matches(&m.subcommand_name().unwrap()).unwrap();
     m.occurrences_of("verbose") + sub.occurrences_of("verbose")
 }
diff --git a/src/main.rs b/src/main.rs
index f80acab..c2b180d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,6 +5,9 @@ extern crate serde_derive;
 
 extern crate serde_yaml;
 
+use std::io::{self, Write};
+use std::process::exit;
+
 mod args;
 mod config;
 mod process;
@@ -14,11 +17,38 @@ mod utils;
 #[cfg(test)]
 mod tests;
 
+use clap::ArgMatches;
+use config::Config;
+
+fn ok_or_exit<T>(res: Result<T, String>) -> T {
+    return match res {
+        Ok(k) => k,
+        Err(err) => {
+            writeln!(io::stderr(), "Error: {:?}", err).unwrap();
+            exit(1);
+        }
+    };
+}
+
+fn get_config(args: &ArgMatches) -> Config {
+    let mut config = ok_or_exit(config::get_config());
+    config.verbosity = args::get_verbose(args);
+    return config;
+}
+
+
 fn main() {
     let args = args::get_matches();
-    if args.subcommand_name().unwrap() == "build" {
-        let mut config = config::get_config().expect("Config error");
-        config.verbosity = args::get_verbose(args);
-        process::build(config);
+    let subcommand = args.subcommand_name().expect("subcommand error");
+
+    match subcommand {
+        "build" => {
+            let config = get_config(&args);
+            ok_or_exit(process::build(config));
+        }
+        cmd => {
+            writeln!(io::stderr(), "Unknown command {}.", cmd).unwrap();
+            exit(1);
+        }
     }
 }
diff --git a/src/process.rs b/src/process.rs
index b1be3d8..84fbfc0 100644
--- a/src/process.rs
+++ b/src/process.rs
@@ -2,7 +2,8 @@ use input::read_input_files;
 use config::Config;
 
 
-pub fn build(config: Config) {
-    let input = read_input_files(config.input).unwrap();
+pub fn build(config: Config) -> Result<(), String> {
+    let input = try!(read_input_files(config.input));
     println!("{}", input);
+    return Ok(());
 }
diff --git a/src/tests/args.rs b/src/tests/args.rs
index fdad971..e3571e8 100644
--- a/src/tests/args.rs
+++ b/src/tests/args.rs
@@ -16,7 +16,7 @@ fn incorrect_subcommand() {
 #[test]
 fn verbose_number() {
     fn get_verbose_level(arg_list: Vec<&str>) -> u64 {
-        return args::get_verbose(args::get_matches_for(arg_list).unwrap());
+        return args::get_verbose(&args::get_matches_for(arg_list).unwrap());
     }
 
     assert_eq!(get_verbose_level(vec!["mdp", "build", "-v"]), 1);