diff --git a/src/akonadi/akonadidatasourcequeries.h b/src/akonadi/akonadidatasourcequeries.h
--- a/src/akonadi/akonadidatasourcequeries.h
+++ b/src/akonadi/akonadidatasourcequeries.h
@@ -55,7 +55,7 @@
     DataSourceResult::Ptr findChildren(Domain::DataSource::Ptr source) const Q_DECL_OVERRIDE;
 
     QString searchTerm() const Q_DECL_OVERRIDE;
-    void setSearchTerm(QString term) Q_DECL_OVERRIDE;
+    void setSearchTerm(const QString &term) Q_DECL_OVERRIDE;
     DataSourceResult::Ptr findSearchTopLevel() const Q_DECL_OVERRIDE;
     DataSourceResult::Ptr findSearchChildren(Domain::DataSource::Ptr source) const Q_DECL_OVERRIDE;
 
diff --git a/src/akonadi/akonadidatasourcequeries.cpp b/src/akonadi/akonadidatasourcequeries.cpp
--- a/src/akonadi/akonadidatasourcequeries.cpp
+++ b/src/akonadi/akonadidatasourcequeries.cpp
@@ -87,7 +87,7 @@
     return m_searchTerm;
 }
 
-void DataSourceQueries::setSearchTerm(QString term)
+void DataSourceQueries::setSearchTerm(const QString &term)
 {
     if (m_searchTerm == term)
         return;
diff --git a/src/domain/datasourcequeries.h b/src/domain/datasourcequeries.h
--- a/src/domain/datasourcequeries.h
+++ b/src/domain/datasourcequeries.h
@@ -69,7 +69,7 @@
     virtual QueryResult<DataSource::Ptr>::Ptr findChildren(DataSource::Ptr source) const = 0;
 
     virtual QString searchTerm() const = 0;
-    virtual void setSearchTerm(QString term) = 0;
+    virtual void setSearchTerm(const QString &term) = 0;
     virtual QueryResult<DataSource::Ptr>::Ptr findSearchTopLevel() const = 0;
     virtual QueryResult<DataSource::Ptr>::Ptr findSearchChildren(DataSource::Ptr source) const = 0;
 
diff --git a/tests/testlib/gennote.h b/tests/testlib/gennote.h
--- a/tests/testlib/gennote.h
+++ b/tests/testlib/gennote.h
@@ -39,7 +39,7 @@
 
     GenNote &withId(Akonadi::Item::Id id);
     GenNote &withParent(Akonadi::Collection::Id id);
-    GenNote &withTags(QList<Akonadi::Tag::Id> ids);
+    GenNote &withTags(const QList<Akonadi::Tag::Id> &ids);
     GenNote &withParentUid(const QString &uid);
     GenNote &withTitle(const QString &title);
     GenNote &withText(const QString &text);
diff --git a/tests/testlib/gennote.cpp b/tests/testlib/gennote.cpp
--- a/tests/testlib/gennote.cpp
+++ b/tests/testlib/gennote.cpp
@@ -55,7 +55,7 @@
     return *this;
 }
 
-GenNote &GenNote::withTags(QList<Akonadi::Tag::Id> ids)
+GenNote &GenNote::withTags(const QList<Akonadi::Tag::Id> &ids)
 {
     auto tags = Akonadi::Tag::List();
     std::transform(ids.constBegin(), ids.constEnd(),
diff --git a/tests/testlib/gentodo.h b/tests/testlib/gentodo.h
--- a/tests/testlib/gentodo.h
+++ b/tests/testlib/gentodo.h
@@ -39,7 +39,7 @@
 
     GenTodo &withId(Akonadi::Item::Id id);
     GenTodo &withParent(Akonadi::Collection::Id id);
-    GenTodo &withTags(QList<Akonadi::Tag::Id> ids);
+    GenTodo &withTags(const QList<Akonadi::Tag::Id> &ids);
     GenTodo &asProject(bool value = true);
     GenTodo &withUid(const QString &uid);
     GenTodo &withParentUid(const QString &uid);
diff --git a/tests/testlib/gentodo.cpp b/tests/testlib/gentodo.cpp
--- a/tests/testlib/gentodo.cpp
+++ b/tests/testlib/gentodo.cpp
@@ -53,7 +53,7 @@
     return *this;
 }
 
-GenTodo &GenTodo::withTags(QList<Akonadi::Tag::Id> ids)
+GenTodo &GenTodo::withTags(const QList<Akonadi::Tag::Id> &ids)
 {
     auto tags = Akonadi::Tag::List();
     std::transform(ids.constBegin(), ids.constEnd(),