diff --git a/src/matriximageprovider.h b/src/matriximageprovider.h
index 6833d41f1..a3736e1c8 100644
--- a/src/matriximageprovider.h
+++ b/src/matriximageprovider.h
@@ -26,7 +26,7 @@ class ThumbnailResponse : public QQuickImageResponse
 {
     Q_OBJECT
 public:
-    ThumbnailResponse(QString mediaId, QSize requestedSize);
+    explicit ThumbnailResponse(QString mediaId, QSize requestedSize);
     ~ThumbnailResponse() override = default;
 
 private Q_SLOTS:
diff --git a/src/models/completionmodel.h b/src/models/completionmodel.h
index 6e80ffc82..6e41a34e9 100644
--- a/src/models/completionmodel.h
+++ b/src/models/completionmodel.h
@@ -71,7 +71,7 @@ public:
     };
     Q_ENUM(Roles)
 
-    CompletionModel(QObject *parent = nullptr);
+    explicit CompletionModel(QObject *parent = nullptr);
 
     /**
      * @brief Get the given role value at the given index.
diff --git a/src/models/mediamessagefiltermodel.h b/src/models/mediamessagefiltermodel.h
index 44938996f..9158aee97 100644
--- a/src/models/mediamessagefiltermodel.h
+++ b/src/models/mediamessagefiltermodel.h
@@ -31,7 +31,7 @@ public:
     };
     Q_ENUM(Roles)
 
-    MediaMessageFilterModel(QObject *parent = nullptr);
+    explicit MediaMessageFilterModel(QObject *parent = nullptr);
 
     /**
      * @brief Custom filter to show only image and video messages.
diff --git a/src/models/messagefiltermodel.h b/src/models/messagefiltermodel.h
index ae85371ca..890d24eb4 100644
--- a/src/models/messagefiltermodel.h
+++ b/src/models/messagefiltermodel.h
@@ -16,7 +16,7 @@ class MessageFilterModel : public QSortFilterProxyModel
 {
     Q_OBJECT
 public:
-    MessageFilterModel(QObject *parent = nullptr);
+    explicit MessageFilterModel(QObject *parent = nullptr);
 
     /**
      * @brief Custom filter function to remove hidden messages.
diff --git a/src/models/publicroomlistmodel.h b/src/models/publicroomlistmodel.h
index eff97c61d..989f7be3c 100644
--- a/src/models/publicroomlistmodel.h
+++ b/src/models/publicroomlistmodel.h
@@ -64,7 +64,7 @@ public:
         IsJoinedRole, /**< Whether the local user has joined the room. */
     };
 
-    PublicRoomListModel(QObject *parent = nullptr);
+    explicit PublicRoomListModel(QObject *parent = nullptr);
 
     /**
      * @brief Get the given role value at the given index.
diff --git a/src/models/pushrulemodel.h b/src/models/pushrulemodel.h
index 1e303baf2..19033fe2d 100644
--- a/src/models/pushrulemodel.h
+++ b/src/models/pushrulemodel.h
@@ -172,7 +172,7 @@ public:
     };
     Q_ENUM(EventRoles)
 
-    PushRuleModel(QObject *parent = nullptr);
+    explicit PushRuleModel(QObject *parent = nullptr);
 
     [[nodiscard]] PushNotificationAction::Action defaultState() const;
     void setDefaultState(PushNotificationAction::Action defaultState);
diff --git a/src/models/reactionmodel.h b/src/models/reactionmodel.h
index acc602dc3..c866bd46a 100644
--- a/src/models/reactionmodel.h
+++ b/src/models/reactionmodel.h
@@ -36,7 +36,7 @@ public:
         HasLocalUser, /**< Whether the local user is in the list of authors. */
     };
 
-    ReactionModel(QObject *parent = nullptr, QList<Reaction> reactions = {}, NeoChatUser *localUser = nullptr);
+    explicit ReactionModel(QObject *parent = nullptr, QList<Reaction> reactions = {}, NeoChatUser *localUser = nullptr);
 
     /**
      * @brief Get the given role value at the given index.
diff --git a/src/neochatuser.h b/src/neochatuser.h
index 797b33909..c9e96d1d9 100644
--- a/src/neochatuser.h
+++ b/src/neochatuser.h
@@ -23,7 +23,7 @@ class NeoChatUser : public Quotient::User
      */
     Q_PROPERTY(QColor color READ color WRITE setColor NOTIFY colorChanged)
 public:
-    NeoChatUser(QString userId, Quotient::Connection *connection);
+    explicit NeoChatUser(QString userId, Quotient::Connection *connection);
 
 public Q_SLOTS:
     QColor color();