diff --git a/mast/cmd.go b/mast/cmd.go
index b0d9a8e..b9f89f0 100644
--- a/mast/cmd.go
+++ b/mast/cmd.go
@@ -70,7 +70,7 @@ func CmdAvailable() ([]string) {
     "open",
     "share",
 
-    // "whois",
+    "whois",
 
     // "search",
 
@@ -83,14 +83,15 @@ func CmdAvailable() ([]string) {
   }
 }
 
-func CmdAutocompleter(input string, knownUsers []string) ([]string) {
+func CmdAutocompleter(input string, knownUsers map[string]string) ([]string) {
   var entries []string
 
   if input == "" {
     return entries
   }
 
-  if input[len(input)-1:] == "@" {
+  if input[len(input)-1:] == "@" ||
+     input == "whois " {
     for _, knownUser := range knownUsers {
       line := input + knownUser
       lineFound := false
@@ -150,6 +151,8 @@ func CmdProcessor(timeline *Timeline, input string) (CmdReturnCode) {
 
     timeline.Switch(TimelineHashtag, &timelineOptions)
     return CodeOk
+  case "whois":
+    return CodeOk
   case "t", "toot":
     return CmdToot(timeline, args, -1, VisibilityPublic)
   case "tp", "tootprivate":
diff --git a/mast/timeline.go b/mast/timeline.go
index f020016..747b344 100644
--- a/mast/timeline.go
+++ b/mast/timeline.go
@@ -31,7 +31,7 @@ type Timeline struct {
   Account                    mastodon.Account
   Toots                      []Toot
   TootIndexStatusIDMappings  map[string]int
-  KnownUsers                 []string
+  KnownUsers                 map[string]string
 }
 
 func NewTimeline(mastodonClient *mastodon.Client) Timeline {
@@ -41,6 +41,7 @@ func NewTimeline(mastodonClient *mastodon.Client) Timeline {
 
     LastRenderedIndex: -1,
     TootIndexStatusIDMappings: make(map[string]int),
+    KnownUsers: make(map[string]string),
   }
 
   return timeline
@@ -111,25 +112,15 @@ func (timeline *Timeline) Load() (error) {
   for i := oldestStatusIndex; i >= 0; i-- {
     status := statuses[i]
 
-    id := string(status.ID)
-    _, exists := timeline.TootIndexStatusIDMappings[id]
+    statusID := string(status.ID)
+    _, exists := timeline.TootIndexStatusIDMappings[statusID]
     if exists == false {
       tootIndex := len(timeline.Toots)
       timeline.Toots =
         append(timeline.Toots, NewToot(timeline.client, status, tootIndex))
 
-      knownUserExists := false
-      for _, knownUser := range timeline.KnownUsers {
-        if knownUser == status.Account.Acct {
-          knownUserExists = true
-        }
-      }
-      if knownUserExists == false {
-        timeline.KnownUsers =
-          append(timeline.KnownUsers, status.Account.Acct)
-      }
-
-      timeline.TootIndexStatusIDMappings[id] = tootIndex
+      timeline.TootIndexStatusIDMappings[statusID] = tootIndex
+      timeline.KnownUsers[string(status.Account.ID)] = status.Account.Acct
     }
   }
 
diff --git a/tui/tui.go b/tui/tui.go
index 9e25a5f..49a2960 100644
--- a/tui/tui.go
+++ b/tui/tui.go
@@ -234,7 +234,7 @@ func (tuiCore *TUICore) ExitCommandMode(force bool) bool {
     tuiCore.App.SetFocus(tuiCore.Stream)
     tuiCore.CmdLine.SetLabelColor(tcell.ColorDefault)
 
-    tuiCore.Prompt = tuiCore.Timeline.Account.Username
+    tuiCore.Prompt = tuiCore.Timeline.Account.Username + "  "
     tuiCore.CmdLine.
       SetLabel(tuiCore.Prompt)