diff --git a/src/common/UsernameSet.cpp b/src/common/UsernameSet.cpp
index d39b8a3e4..964b6c0a7 100644
--- a/src/common/UsernameSet.cpp
+++ b/src/common/UsernameSet.cpp
@@ -99,6 +99,11 @@ bool Prefix::operator==(const Prefix &other) const
            std::tie(other.first, other.second);
 }
 
+bool Prefix::operator!=(const Prefix &other) const
+{
+    return !(*this == other);
+}
+
 bool Prefix::isStartOf(const QString &string) const
 {
     if (string.size() == 0)
diff --git a/src/common/UsernameSet.hpp b/src/common/UsernameSet.hpp
index f33d7d7e6..f07911513 100644
--- a/src/common/UsernameSet.hpp
+++ b/src/common/UsernameSet.hpp
@@ -12,6 +12,7 @@ class Prefix
 public:
     Prefix(const QString &string);
     bool operator==(const Prefix &other) const;
+    bool operator!=(const Prefix &other) const;
     bool isStartOf(const QString &string) const;
 
 private: