diff --git a/src/Parser.c b/src/Parser.c
index d46da35..62ba03a 100644
--- a/src/Parser.c
+++ b/src/Parser.c
@@ -323,6 +323,28 @@ ParseServerName(char **str, ServerPart *out)
 
     return 1;
 }
+int
+ParseServerPart(char *str, ServerPart *part)
+{
+    /* This is a wrapper behind the internal ParseServerName. */
+    if (!str || !part)
+    {
+        return 0;
+    }
+    return ParseServerName(&str, part);
+}
+void
+ServerPartFree(ServerPart part)
+{
+    if (part.hostname)
+    {
+        Free(part.hostname);
+    }
+    if (part.port)
+    {
+        Free(part.port);
+    }
+}
 
 int
 ParseCommonID(char *str, CommonID *id)
@@ -406,14 +428,7 @@ CommonIDFree(CommonID id)
     {
         Free(id.local);
     }
-    if (id.server.hostname)
-    {
-        Free(id.server.hostname);
-    }
-    if (id.server.port)
-    {
-        Free(id.server.port);
-    }
+    ServerPartFree(id.server);
 }
 int
 ValidCommonID(char *str, char sigil)
@@ -432,6 +447,19 @@ ValidCommonID(char *str, char sigil)
     return ret;
 }
 char *
+ParserRecomposeServerPart(ServerPart serverPart)
+{
+    if (serverPart.hostname && serverPart.port)
+    {
+        return StrConcat(3, serverPart.hostname, ":", serverPart.port);
+    }
+    if (serverPart.hostname)
+    {
+        return StrDuplicate(serverPart.hostname);
+    }
+    return NULL;
+}
+char *
 ParserRecomposeCommonID(CommonID id)
 {
     char *ret = Malloc(2);
@@ -442,19 +470,33 @@ ParserRecomposeCommonID(CommonID id)
     {
         char *tmp = StrConcat(2, ret, id.local);
         Free(ret);
+
         ret = tmp;
     }
     if (id.server.hostname)
     {
-        char *tmp = StrConcat(3, ret, ":", id.server.hostname);
-        Free(ret);
-        ret = tmp;
-    }
-    if (id.server.port)
-    {
-        char *tmp = StrConcat(3, ret, ":", id.server.port);
+        char *server = ParserRecomposeServerPart(id.server);
+        char *tmp = StrConcat(4, "@", ret, ":", server);
         Free(ret);
+        Free(server);
+
         ret = tmp;
     }
     return ret;
 }
+int
+ParserServerNameEquals(ServerPart serverPart, char *str)
+{
+    char *idServer;
+    int ret;
+    if (!str)
+    {
+        return 0;
+    }
+    idServer = ParserRecomposeServerPart(serverPart);
+
+    ret = StrEquals(idServer, str);
+    Free(idServer);
+    
+    return ret;
+}
diff --git a/src/Routes/RouteAliasDirectory.c b/src/Routes/RouteAliasDirectory.c
index 4c3938e..137e1ce 100644
--- a/src/Routes/RouteAliasDirectory.c
+++ b/src/Routes/RouteAliasDirectory.c
@@ -118,18 +118,21 @@ ROUTE_IMPL(RouteAliasDirectory, path, argp)
             {
                 HashMap *newAlias;
                 char *id;
+                char *serverPart;
 
-                /* Check for server name. 
-                 * TODO: Take the port into account, that might need a 
-                 * refactor for it to use a ServerPart */
-                if (!StrEquals(aliasID.server.hostname, config->serverName))
+                serverPart = ParserRecomposeServerPart(aliasID.server);
+                if (!StrEquals(serverPart, config->serverName))
                 {
                     msg = "Invalid server name.";
                     HttpResponseStatus(args->context, HTTP_BAD_REQUEST);
                     response = MatrixErrorCreate(M_INVALID_PARAM, msg);
+
+                    Free(serverPart);
                     goto finish;
                 }
 
+                Free(serverPart);
+
                 if (JsonGet(aliases, 2, "alias", alias))
                 {
                     HttpResponseStatus(args->context, HTTP_CONFLICT);
diff --git a/src/Routes/RouteFilter.c b/src/Routes/RouteFilter.c
index c2ead37..c8f4fa8 100644
--- a/src/Routes/RouteFilter.c
+++ b/src/Routes/RouteFilter.c
@@ -64,7 +64,7 @@ ROUTE_IMPL(RouteFilter, path, argp)
     HashMap *response = NULL;
 
     User *user = NULL;
-    UserId *id = NULL;
+    CommonID *id = NULL;
     char *token = NULL;
 
     char *serverName = NULL;
@@ -97,7 +97,7 @@ ROUTE_IMPL(RouteFilter, path, argp)
         goto finish;
     }
 
-    if (!StrEquals(id->server, serverName))
+    if (!ParserServerNameEquals(id->server, serverName))
     {
         msg = "Cannot use /filter for non-local users.";
         HttpResponseStatus(args->context, HTTP_UNAUTHORIZED);
@@ -119,7 +119,7 @@ ROUTE_IMPL(RouteFilter, path, argp)
         goto finish;
     }
 
-    if (!StrEquals(id->localpart, UserGetName(user)))
+    if (!StrEquals(id->local, UserGetName(user)))
     {
         msg = "Unauthorized to use /filter.";
         HttpResponseStatus(args->context, HTTP_UNAUTHORIZED);
diff --git a/src/Routes/RouteLogin.c b/src/Routes/RouteLogin.c
index 158629d..6234f15 100644
--- a/src/Routes/RouteLogin.c
+++ b/src/Routes/RouteLogin.c
@@ -49,7 +49,7 @@ ROUTE_IMPL(RouteLogin, path, argp)
     LoginRequest loginRequest;
     LoginRequestUserIdentifier userIdentifier;
 
-    UserId *userId = NULL;
+    CommonID *userId = NULL;
 
     Db *db = args->matrixArgs->db;
 
@@ -160,8 +160,8 @@ ROUTE_IMPL(RouteLogin, path, argp)
                 break;
             }
 
-            if (!StrEquals(userId->server, config.serverName)
-                || !UserExists(db, userId->localpart))
+            if (!ParserServerNameEquals(userId->server, config.serverName)
+                || !UserExists(db, userId->local))
             {
                 msg = "Unknown user ID.";
                 HttpResponseStatus(args->context, HTTP_FORBIDDEN);
@@ -175,7 +175,7 @@ ROUTE_IMPL(RouteLogin, path, argp)
             password = loginRequest.password;
             refreshToken = loginRequest.refresh_token;
 
-            user = UserLock(db, userId->localpart);
+            user = UserLock(db, userId->local);
 
             if (!user)
             {
diff --git a/src/Routes/RouteUserProfile.c b/src/Routes/RouteUserProfile.c
index 5c1af7b..4c438b0 100644
--- a/src/Routes/RouteUserProfile.c
+++ b/src/Routes/RouteUserProfile.c
@@ -40,7 +40,7 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
     HashMap *request = NULL;
     HashMap *response = NULL;
 
-    UserId *userId = NULL;
+    CommonID *userId = NULL;
     User *user = NULL;
 
     char *serverName;
@@ -73,7 +73,7 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
         response = MatrixErrorCreate(M_INVALID_PARAM, msg);
         goto finish;
     }
-    if (strcmp(userId->server, serverName))
+    if (!ParserServerNameEquals(userId->server, serverName))
     {
         /* TODO: Implement lookup over federation. */
         msg =   "User profile endpoint currently doesn't support lookup over "
@@ -87,7 +87,7 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
     switch (HttpRequestMethodGet(args->context))
     {
         case HTTP_GET:
-            user = UserLock(db, userId->localpart);
+            user = UserLock(db, userId->local);
             if (!user)
             {
                 msg = "Couldn't lock user.";
@@ -147,11 +147,11 @@ ROUTE_IMPL(RouteUserProfile, path, argp)
                     StrEquals(entry, "avatar_url"))
                 {
                     /* Check if user has privilege to do that action. */
-                    if (StrEquals(userId->localpart, UserGetName(user)))
+                    if (StrEquals(userId->local, UserGetName(user)))
                     {
                         value = JsonValueAsString(HashMapGet(request, entry));
-                        /* TODO: Make UserSetProfile notify other
-                         * parties of the change */
+                        /* TODO: Make UserSetProfile notify other parties of 
+                         * the change */
                         UserSetProfile(user, entry, value);
                         response = HashMapCreate();
                         goto finish;
diff --git a/src/Uia.c b/src/Uia.c
index 2c0abb8..ff00b06 100644
--- a/src/Uia.c
+++ b/src/Uia.c
@@ -351,7 +351,7 @@ UiaComplete(Array * flows, HttpServerContext * context, Db * db,
         char *password = JsonValueAsString(HashMapGet(auth, "password"));
         HashMap *identifier = JsonValueAsObject(HashMapGet(auth, "identifier"));
         char *type;
-        UserId *userId;
+        CommonID *userId;
         User *user;
 
         if (!password || !identifier)
@@ -366,7 +366,8 @@ UiaComplete(Array * flows, HttpServerContext * context, Db * db,
                              config.serverName);
 
         if (!type || !StrEquals(type, "m.id.user")
-         || !userId || !StrEquals(userId->server, config.serverName))
+         || !userId 
+         || !ParserServerNameEquals(userId->server, config.serverName))
         {
             HttpResponseStatus(context, HTTP_UNAUTHORIZED);
             ret = BuildResponse(flows, db, response, session, dbRef);
@@ -374,7 +375,7 @@ UiaComplete(Array * flows, HttpServerContext * context, Db * db,
             goto finish;
         }
 
-        user = UserLock(db, userId->localpart);
+        user = UserLock(db, userId->local);
         if (!user)
         {
             HttpResponseStatus(context, HTTP_UNAUTHORIZED);
diff --git a/src/User.c b/src/User.c
index 20a4289..1fc872d 100644
--- a/src/User.c
+++ b/src/User.c
@@ -884,10 +884,11 @@ finish:
     return arr;
 }
 
-UserId *
+CommonID *
 UserIdParse(char *id, char *defaultServer)
 {
-    UserId *userId;
+    CommonID *userId;
+    char *server;
 
     if (!id)
     {
@@ -900,52 +901,38 @@ UserIdParse(char *id, char *defaultServer)
         return NULL;
     }
 
-    userId = Malloc(sizeof(UserId));
+    userId = Malloc(sizeof(CommonID));
     if (!userId)
     {
         goto finish;
     }
+    memset(userId, 0, sizeof(CommonID));
 
     /* Fully-qualified user ID */
     if (*id == '@')
     {
-        /* TODO: Just use the CommonID. */
-        CommonID commonID;
-        commonID.sigil = '\0';
-        commonID.local = NULL;
-        commonID.server.hostname = NULL;
-        commonID.server.port = NULL;
-        if (!ParseCommonID(id, &commonID) || !commonID.server.hostname)
+        if (!ParseCommonID(id, userId) || !userId->server.hostname)
         {
-            Free(userId);
-            Free(commonID.local);
-            if (commonID.server.hostname)
-            {
-                Free(commonID.server.hostname);
-            }
+            UserIdFree(userId);
+
             userId = NULL;
             goto finish;
         }
-
-        userId->localpart = commonID.local;
-        userId->server = commonID.server.hostname;
-        if (commonID.server.port)
-        {
-            Free(commonID.server.port);
-        }
     }
     else
     {
         /* Treat it as just a localpart */
-        userId->localpart = StrDuplicate(id);
-        userId->server = StrDuplicate(defaultServer);
+        userId->local = StrDuplicate(id);
+        ParseServerPart(defaultServer, &userId->server);
     }
 
-    if (!UserHistoricalValidate(userId->localpart, userId->server))
+    server = ParserRecomposeServerPart(userId->server);
+    if (!UserHistoricalValidate(userId->local, server))
     {
         UserIdFree(userId);
         userId = NULL;
     }
+    Free(server);
 
 finish:
     Free(id);
@@ -953,12 +940,11 @@ finish:
 }
 
 void
-UserIdFree(UserId * id)
+UserIdFree(CommonID * id)
 {
     if (id)
     {
-        Free(id->localpart);
-        Free(id->server);
+        CommonIDFree(*id);
         Free(id);
     }
 }
diff --git a/src/include/Parser.h b/src/include/Parser.h
index 405caf1..bd57dc0 100644
--- a/src/include/Parser.h
+++ b/src/include/Parser.h
@@ -58,6 +58,12 @@ typedef struct CommonID {
  * by the [matrix] specification.
  */
 extern int ParseCommonID(char *, CommonID *);
+
+/** 
+ * Parses the server part in a common identifier.
+ */
+extern int ParseServerPart(char *, ServerPart *);
+
 /** 
  * Checks whenever the string is a valid common ID with the correct sigil.
  */
@@ -66,7 +72,15 @@ extern int ValidCommonID(char *, char);
 /** 
  * Frees a CommonID's values. Note that it doesn't free the CommonID itself.
  */
-extern void CommonIDFree(CommonID id);
+extern void CommonIDFree(CommonID);
+
+/** 
+ * Frees a ServerPart's values. Note that it doesn't free the ServerPart 
+ * itself, and that 
+ * .Fn CommonIDFree 
+ * automatically deals with its server part.
+ */
+extern void ServerPartFree(ServerPart);
 
 /**
  * Recompose a Common ID into a string which lives in the heap, and must 
@@ -75,5 +89,17 @@ extern void CommonIDFree(CommonID id);
  */
 extern char * ParserRecomposeCommonID(CommonID);
 
+/**
+ * Recompose a server part into a string which lives in the heap, and must 
+ * therefore be freed with 
+ * .Fn Free .
+ */
+extern char * ParserRecomposeServerPart(ServerPart);
+
+/**
+ * Compares whenever a ServerName is equivalent to a server name string.
+ */
+extern int ParserServerNameEquals(ServerPart, char *);
+
 
 #endif                             /* TELODENDRIA_PARSER_H */
diff --git a/src/include/User.h b/src/include/User.h
index 6eb5530..f84ac94 100644
--- a/src/include/User.h
+++ b/src/include/User.h
@@ -43,6 +43,8 @@
 #include <Cytoplasm/Db.h>
 #include <Cytoplasm/Json.h>
 
+#include <Parser.h>
+
 /**
  * Many functions here operate on an opaque user structure.
  */
@@ -88,15 +90,6 @@ typedef struct UserLoginInfo
     char *refreshToken;
 } UserLoginInfo;
 
-/**
- * A description of a Matrix user ID.
- */
-typedef struct UserId
-{
-    char *localpart;
-    char *server;
-} UserId;
-
 /**
  * Take a localpart and domain as separate parameters and validate them
  * against the rules of the Matrix specification. The reasion the
@@ -303,15 +296,15 @@ extern Array *UserEncodePrivileges(int);
 extern int UserDecodePrivilege(const char *);
 
 /**
- * Parse either a localpart or a fully qualified Matrix ID. If the
+ * Parse either a localpart or a fully qualified Matrix common ID. If the
  * first argument is a localpart, then the second argument is used as
  * the server name.
  */
-extern UserId * UserIdParse(char *, char *);
+extern CommonID * UserIdParse(char *, char *);
 
 /**
- * Free the memory associated with the parsed Matrix ID.
+ * Frees the user's common ID and the memory allocated for it.
  */
-extern void UserIdFree(UserId *);
+extern void UserIdFree(CommonID *);
 
 #endif                             /* TELODENDRIA_USER_H */