diff --git a/drivers/common/include/orm/drivers/sqldatabase.hpp b/drivers/common/include/orm/drivers/sqldatabase.hpp
index 2fff5c5cb..eb09623b8 100644
--- a/drivers/common/include/orm/drivers/sqldatabase.hpp
+++ b/drivers/common/include/orm/drivers/sqldatabase.hpp
@@ -24,7 +24,7 @@ namespace Orm::Drivers
         // To access the private constructors and d smart pointer (private impl.)
         friend SqlDatabaseManager;
         // To access the d smart pointer (private implementation)
-        friend class SqlDatabasePrivate;
+        friend SqlDatabasePrivate;
 
         /*! Alias for the NotNull. */
         template<typename T>
diff --git a/drivers/common/include/orm/drivers/sqldriver.hpp b/drivers/common/include/orm/drivers/sqldriver.hpp
index 0bf61ee91..adaae90f7 100644
--- a/drivers/common/include/orm/drivers/sqldriver.hpp
+++ b/drivers/common/include/orm/drivers/sqldriver.hpp
@@ -18,6 +18,7 @@ namespace Orm::Drivers
 {
 
     class DummySqlError;
+    class SqlDatabase;
     class SqlDriverPrivate;
     class SqlRecord;
     class SqlResult;
@@ -29,7 +30,7 @@ namespace Orm::Drivers
         Q_DECLARE_PRIVATE(SqlDriver) // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
 
         // To access the setConnectionName()
-        friend class SqlDatabase;
+        friend SqlDatabase;
 
     protected:
         /*! Protected constructor. */
diff --git a/drivers/common/include/orm/drivers/sqlresult.hpp b/drivers/common/include/orm/drivers/sqlresult.hpp
index 643370fc8..98595b4c7 100644
--- a/drivers/common/include/orm/drivers/sqlresult.hpp
+++ b/drivers/common/include/orm/drivers/sqlresult.hpp
@@ -18,6 +18,7 @@ namespace Orm::Drivers
 {
 
     class SqlDriver;
+    class SqlQuery;
     class SqlRecord;
     class SqlResultPrivate;
 
@@ -28,7 +29,7 @@ namespace Orm::Drivers
         Q_DECLARE_PRIVATE(SqlResult) // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
 
         // To access practically everything, all logic is defined in the SqlResult
-        friend class SqlQuery;
+        friend SqlQuery;
 
     protected:
         /*! Constructor. */
diff --git a/drivers/mysql/include/orm/drivers/mysql/mysqldriver.hpp b/drivers/mysql/include/orm/drivers/mysql/mysqldriver.hpp
index 8f0943a6a..b575ba962 100644
--- a/drivers/mysql/include/orm/drivers/mysql/mysqldriver.hpp
+++ b/drivers/mysql/include/orm/drivers/mysql/mysqldriver.hpp
@@ -13,6 +13,7 @@ namespace Orm::Drivers::MySql
 {
 
     class MySqlDriverPrivate;
+    class MySqlResultPrivate;
 
     /*! MySQL database driver. */
     class TINYDRIVERS_EXPORT MySqlDriver final :
@@ -25,7 +26,7 @@ namespace Orm::Drivers::MySql
         /* To access MySqlDriver::d_func() through the MySqlResultPrivate::drv_d_func(),
            what means that the MySqlResultPrivate will have access
            to the MySqlDriverPrivate. */
-        friend class MySqlResultPrivate;
+        friend MySqlResultPrivate;
 
     public:
         /*! Default constructor. */
diff --git a/include/orm/concerns/countsqueries.hpp b/include/orm/concerns/countsqueries.hpp
index 17d98296d..5857447b3 100644
--- a/include/orm/concerns/countsqueries.hpp
+++ b/include/orm/concerns/countsqueries.hpp
@@ -22,13 +22,15 @@ class DatabaseConnection;
 namespace Concerns
 {
 
+    class ManagesTransactions;
+
     /*! Counts the number of executed queries and the elapsed time of queries. */
     class TINYORM_EXPORT CountsQueries
     {
         Q_DISABLE_COPY_MOVE(CountsQueries)
 
         // To access hitTransactionalCounters() method
-        friend class ManagesTransactions;
+        friend ManagesTransactions;
 
     public:
         /*! Default constructor. */
diff --git a/include/orm/configurations/configurationparser.hpp b/include/orm/configurations/configurationparser.hpp
index ab7871173..02fc4b2a4 100644
--- a/include/orm/configurations/configurationparser.hpp
+++ b/include/orm/configurations/configurationparser.hpp
@@ -23,7 +23,7 @@ namespace Orm::Configurations
         Q_DISABLE_COPY_MOVE(ConfigurationParser)
 
         // To access config()
-        friend class ConfigurationOptionsParser;
+        friend ConfigurationOptionsParser;
 
     public:
         /*! Default constructor. */
diff --git a/include/orm/databaseconnection.hpp b/include/orm/databaseconnection.hpp
index 64aa7f960..3c4df25ea 100644
--- a/include/orm/databaseconnection.hpp
+++ b/include/orm/databaseconnection.hpp
@@ -63,7 +63,7 @@ namespace Orm
            https://community.kde.org/Policies/Binary_Compatibility_Issues_With_C++ */
 #ifdef TINYORM_MYSQL_PING
         // To access logConnected()/logDisconnected() methods
-        friend class MySqlConnection;
+        friend MySqlConnection;
 #endif
 
         /*! Alias for the QueryError exception. */