diff --git a/src/config/mod.rs b/src/config/mod.rs
index 475297b..3f225d9 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -9,10 +9,16 @@ use std::io::Read;
 pub mod consts;
 pub mod csl;
 
+#[derive(Debug, Serialize, Deserialize, Eq, PartialEq, Hash, Clone)]
+pub enum OutputType {
+    PDF,
+    HTML
+}
+
 #[derive(Debug, Serialize, Deserialize, Default, Clone)]
 pub struct Config {
     input: Vec<PathBuf>,
-    output: HashMap<String, PathBuf>,
+    output: HashMap<OutputType, PathBuf>,
     pub title: String,
 
     #[serde(default = "default_verbosity")]
@@ -30,11 +36,11 @@ pub struct References {
 
 
 impl Config {
-    pub fn absolute_output(&self, output_type: String) -> PathBuf {
+    pub fn absolute_output(&self, output_type: OutputType) -> PathBuf {
         return resolve_path(self.output.get(&output_type).unwrap());
     }
 
-    pub fn has_output(&self, output_type: String) -> bool {
+    pub fn has_output(&self, output_type: OutputType) -> bool {
         return self.output.contains_key(&output_type);
     }
 
diff --git a/src/main.rs b/src/main.rs
index f498e4e..59dc99f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -52,7 +52,6 @@ fn get_config(args: ArgMatches) -> Config {
 fn main() {
     let args = args::get_matches();
     let subcommand = args.subcommand_name().expect("subcommand error");
-
     match subcommand {
         "build" => {
             let config = get_config(args.clone());
diff --git a/src/output/mod.rs b/src/output/mod.rs
index f845b15..1a17c02 100644
--- a/src/output/mod.rs
+++ b/src/output/mod.rs
@@ -1,9 +1,9 @@
-use config::Config;
+use config::{Config, OutputType};
 
 pub mod pdf;
 
 pub fn output(config: Config, output: String) -> Result<(), String> {
-    if config.has_output("pdf".into()) {
+    if config.has_output(OutputType::PDF) {
         try!(pdf::output(config, output));
     }
     return Ok(());
diff --git a/src/output/pdf/mod.rs b/src/output/pdf/mod.rs
index 4352c77..0bcf1fe 100644
--- a/src/output/pdf/mod.rs
+++ b/src/output/pdf/mod.rs
@@ -1,4 +1,4 @@
-use config::Config;
+use config::{Config, OutputType};
 use utils::result_override;
 
 use std::error::Error;
@@ -25,7 +25,7 @@ fn create_builder<'a>(config: Config, builder: &'a mut PdfBuilder) -> &'a mut Pd
 }
 
 pub fn output(config: Config, html: String) -> Result<(), String> {
-    let output_location = &config.absolute_output("pdf".into());
+    let output_location = &config.absolute_output(OutputType::PDF);
     let mut pdf_app =
         try!(result_override(PdfApplication::new(), "Failed to create PDF Application".into()));
     let mut base_builder = pdf_app.builder();
diff --git a/test-files/mdp.yml b/test-files/mdp.yml
index 6141439..08af668 100644
--- a/test-files/mdp.yml
+++ b/test-files/mdp.yml
@@ -6,7 +6,7 @@ input:
     - ipsum.md
     - end.md
 output:
-    pdf: output.pdf
+    PDF: output.pdf
 title: test title
 references:
     bibliography: bib.yaml