diff --git a/src/catalog.rs b/src/catalog.rs
new file mode 100644
index 0000000..471280a
--- /dev/null
+++ b/src/catalog.rs
@@ -0,0 +1,50 @@
+// (catalog_name, (username, password))
+pub type CatalogDefinition<'a> = (&'a str, Login<'a>);
+pub type Login<'a> = Option<(&'a str, &'a str)>;
+
+pub static ALIASES: &[(&str, CatalogDefinition)] = &[
+    ("DS_WS1617", ("16w-diskrete-strukturen", None)),
+    ("EIDI_WS1617", ("eidi1-2016", Some(("eidi-2016", "PGdP.16")))),
+    ("ERA_WS1617", ("era-2016", None)),
+
+    ("GAD_SS17", ("17s-grundlagen-algorithmen-und-datenstrukturen", None)),
+    ("LA_SS17", ("17s-lineare-algebra-fuer-informatik", None)),
+    // EIST is on a Nextcloud
+];
+
+pub static ALIAS_ALIASES: &[(&str, &str)] = &[
+    ("DS", "DS_WS1617"),
+    ("EIDI", "EIDI_WS1617"),
+    ("ERA", "ERA_WS1617"),
+
+    ("GAD", "GAD_SS17"),
+    ("LA", "LA_SS17"),
+];
+
+pub fn resolve_alias(mut query: &str) -> Option<CatalogDefinition> {
+    for &(alias_alias, alias) in ALIAS_ALIASES {
+        if query == alias_alias {
+            query = alias;
+        }
+    }
+
+    for &(alias_name, def) in ALIASES {
+        if query == alias_name {
+            return Some(def);
+        }
+    }
+
+    None
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn check_alias_aliases() {
+        for &(alias, _) in ALIAS_ALIASES {
+            assert!(resolve_alias(alias).is_some());
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index e8a755c..7254b27 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,6 +7,8 @@ extern crate lazy_static;
 extern crate reqwest;
 extern crate zip;
 
+mod catalog;
+
 use std::env;
 use std::process::Command;
 use std::collections::HashMap;
@@ -23,7 +25,7 @@ use reqwest::header::{Cookie, Charset, SetCookie};
 use reqwest::header::{ContentDisposition, DispositionType, DispositionParam};
 use zip::ZipArchive;
 
-use catalogs::*;
+use catalog::*;
 
 // TODO: Old "Publish To Go" packages get sweeped from the server and you have to request a new one;
 //       Implement this
@@ -31,20 +33,6 @@ use catalogs::*;
 // TODO: Add aliases with semester postfix so other can contribute aliases; move to separate file
 //       split into files in general?
 
-mod catalogs {
-    type Login = Option<(&'static str, &'static str)>;
-    type CatalogDef = (&'static str, Login);
-
-    // (catalog_name, (username, password))
-    pub const DS: CatalogDef = ("16w-diskrete-strukturen", None);
-    pub const EIDI: CatalogDef = ("eidi1-2016", Some(("eidi-2016", "PGdP.16")));
-    pub const ERA: CatalogDef = ("era-2016", None);
-
-    pub const GAD: CatalogDef = ("17s-grundlagen-algorithmen-und-datenstrukturen", None);
-    pub const LA: CatalogDef = ("17s-lineare-algebra-fuer-informatik", None);
-    // EIST is on a Nextcloud
-}
-
 const MAX_RETRIES: u8 = 10;
 
 lazy_static! {
@@ -266,22 +254,16 @@ fn main() {
                  .takes_value(true))
         .get_matches();
 
-    let catalog_def = match matches.value_of("CATALOG_NAME").unwrap() {
-        "DS" => DS,
-        "EIDI" => EIDI,
-        "ERA" => ERA,
-        "GAD" => GAD,
-        "LA" => LA,
-        n => {
-            if let Some(username) = matches.value_of("username") {
-                let password = matches.value_of("password").unwrap();
-                (n, Some((username, password)))
-            } else {
-                (n, None)
-            }
-        }
+    let catalog_name = matches.value_of("CATALOG_NAME").unwrap();
+    let login = if let Some(username) = matches.value_of("username") {
+        let password = matches.value_of("password").unwrap();
+        Some((username, password))
+    } else {
+        None
     };
 
+    let catalog_def = resolve_alias(catalog_name).unwrap_or((catalog_name, login));
+
     let out_dir = Path::new(matches.value_of("OUTPUT_DIRECTORY").unwrap());
     if out_dir.exists() {
         assert!(out_dir.is_dir());