diff --git a/CMakeLists.txt b/CMakeLists.txt
index a8d41aeea377..1ec3f95d89bc 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -91,7 +91,8 @@ include(GetGitRevisionDescription)
 get_git_head_revision(GIT_REFSPEC GIT_SHA1)
 
 add_definitions(
-    -DQT_DISABLE_DEPRECATED_BEFORE=0x000000
+    -DQT_DISABLE_DEPRECATED_BEFORE=0x051200
+    -DQT_DEPRECATED_WARNINGS
     -DQT_USE_QSTRINGBUILDER
     -DQT_MESSAGELOGCONTEXT #enable function name and line number in debug output
 )
diff --git a/src/gui/networksettings.cpp b/src/gui/networksettings.cpp
index 7e00b97ac5f9..ba908b54e044 100644
--- a/src/gui/networksettings.cpp
+++ b/src/gui/networksettings.cpp
@@ -61,7 +61,7 @@ NetworkSettings::NetworkSettings(QWidget *parent)
 
         connect(_ui->typeComboBox, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this,
             &NetworkSettings::saveProxySettings);
-        connect(_ui->proxyButtonGroup, static_cast<void (QButtonGroup::*)(int)>(&QButtonGroup::buttonClicked), this,
+        connect(_ui->proxyButtonGroup, &QButtonGroup::buttonClicked, this,
             &NetworkSettings::saveProxySettings);
         connect(_ui->hostLineEdit, &QLineEdit::editingFinished, this, &NetworkSettings::saveProxySettings);
         connect(_ui->userLineEdit, &QLineEdit::editingFinished, this, &NetworkSettings::saveProxySettings);
diff --git a/src/libsync/propagatedownload.cpp b/src/libsync/propagatedownload.cpp
index 0bb179b8168c..374289bc7877 100644
--- a/src/libsync/propagatedownload.cpp
+++ b/src/libsync/propagatedownload.cpp
@@ -865,8 +865,7 @@ void PropagateDownloadFile::slotGetFinished()
     // of the compressed data. See QTBUG-73364.
     const auto contentEncoding = job->reply()->rawHeader("content-encoding").toLower();
     if ((contentEncoding == "gzip" || contentEncoding == "deflate")
-        && (job->reply()->attribute(QNetworkRequest::Http2WasUsedAttribute).toBool()
-         || job->reply()->attribute(QNetworkRequest::SpdyWasUsedAttribute).toBool())) {
+        && job->reply()->attribute(QNetworkRequest::Http2WasUsedAttribute).toBool()) {
         bodySize = 0;
         hasSizeHeader = false;
     }