diff --git a/src/common/CompletionModel.cpp b/src/common/CompletionModel.cpp
index ce07b25f..8ccafb8e 100644
--- a/src/common/CompletionModel.cpp
+++ b/src/common/CompletionModel.cpp
@@ -82,7 +82,8 @@ void CompletionModel::refresh(const QString &prefix)
     if (prefix.length() < 2) return;
 
     auto addString = [&](const QString &str, TaggedString::Type type) {
-        if (str.startsWith(prefix)) this->items_.emplace(str + " ", type);
+        if (str.startsWith(prefix, Qt::CaseInsensitive))
+            this->items_.emplace(str + " ", type);
     };
 
     if (auto channel = dynamic_cast<TwitchChannel *>(&this->channel_)) {
diff --git a/src/common/UsernameSet.cpp b/src/common/UsernameSet.cpp
index 4356772a..064b6cf5 100644
--- a/src/common/UsernameSet.cpp
+++ b/src/common/UsernameSet.cpp
@@ -85,8 +85,8 @@ UsernameSet::ConstIterator UsernameSet::Range::end()
 //
 
 Prefix::Prefix(const QString &string)
-    : first(string.size() >= 1 ? string[0] : '\0')
-    , second(string.size() >= 2 ? string[1] : '\0')
+    : first(string.size() >= 1 ? string[0].toLower() : '\0')
+    , second(string.size() >= 2 ? string[1].toLower() : '\0')
 {
 }
 
@@ -101,9 +101,11 @@ bool Prefix::isStartOf(const QString &string) const
     if (string.size() == 0) {
         return this->first == QChar('\0') && this->second == QChar('\0');
     } else if (string.size() == 1) {
-        return this->first == string[0] && this->second == QChar('\0');
+        return this->first == string[0].toLower() &&
+               this->second == QChar('\0');
     } else {
-        return this->first == string[0] && this->second == string[1];
+        return this->first == string[0].toLower() &&
+               this->second == string[1].toLower();
     }
 }