diff --git a/src/base/bittorrent/speedmonitor.h b/src/base/bittorrent/speedmonitor.h
index 86ececd0b..6bb7c97c9 100644
--- a/src/base/bittorrent/speedmonitor.h
+++ b/src/base/bittorrent/speedmonitor.h
@@ -38,34 +38,30 @@
 template<typename T>
 struct Sample
 {
-    Sample()
-        : download()
-        , upload()
+    constexpr Sample() = default;
+
+    constexpr Sample(const T dl, const T ul)
+        : download {dl}
+        , upload {ul}
     {
     }
 
-    Sample(T dl, T ul)
-        : download(dl)
-        , upload(ul)
-    {
-    }
-
-    Sample<T> &operator+=(const Sample<T> &other)
+    constexpr Sample<T> &operator+=(const Sample<T> &other)
     {
         download += other.download;
-        upload   += other.upload;
+        upload += other.upload;
         return *this;
     }
 
-    Sample<T> &operator-=(const Sample<T> &other)
+    constexpr Sample<T> &operator-=(const Sample<T> &other)
     {
         download -= other.download;
-        upload   -= other.upload;
+        upload -= other.upload;
         return *this;
     }
 
-    T download;
-    T upload;
+    T download {};
+    T upload {};
 };
 
 typedef Sample<qlonglong> SpeedSample;
diff --git a/src/base/net/downloadhandlerimpl.cpp b/src/base/net/downloadhandlerimpl.cpp
index 93a2c33eb..75a0318bd 100644
--- a/src/base/net/downloadhandlerimpl.cpp
+++ b/src/base/net/downloadhandlerimpl.cpp
@@ -32,6 +32,7 @@
 #include <QTemporaryFile>
 #include <QUrl>
 
+#include "base/3rdparty/expected.hpp"
 #include "base/utils/fs.h"
 #include "base/utils/gzip.h"
 #include "base/utils/io.h"
@@ -41,18 +42,14 @@ const int MAX_REDIRECTIONS = 20;  // the common value for web browsers
 
 namespace
 {
-    bool saveToFile(const QByteArray &replyData, QString &filePath)
+    nonstd::expected<QString, QString> saveToTempFile(const QByteArray &data)
     {
-        if (!filePath.isEmpty())
-            return Utils::IO::saveToFile(filePath, replyData).has_value();
-
         QTemporaryFile file {Utils::Fs::tempPath()};
-        if (!file.open() || (file.write(replyData) != replyData.length()) || !file.flush())
-            return false;
+        if (!file.open() || (file.write(data) != data.length()) || !file.flush())
+            return nonstd::make_unexpected(file.errorString());
 
         file.setAutoRemove(false);
-        filePath = file.fileName();
-        return true;
+        return file.fileName();
     }
 }
 
@@ -130,11 +127,23 @@ void DownloadHandlerImpl::processFinishedDownload()
 
     if (m_downloadRequest.saveToFile())
     {
-        QString filePath {m_downloadRequest.destFileName()};
-        if (saveToFile(m_result.data, filePath))
-            m_result.filePath = filePath;
+        const QString destinationPath = m_downloadRequest.destFileName();
+        if (destinationPath.isEmpty())
+        {
+            const nonstd::expected<QString, QString> result = saveToTempFile(m_result.data);
+            if (result)
+                m_result.filePath = result.value();
+            else
+                setError(tr("I/O Error: %1").arg(result.error()));
+        }
         else
-            setError(tr("I/O Error"));
+        {
+            const nonstd::expected<void, QString> result = Utils::IO::saveToFile(destinationPath, m_result.data);
+            if (result)
+                m_result.filePath = destinationPath;
+            else
+                setError(tr("I/O Error: %1").arg(result.error()));
+        }
     }
 
     finish();
diff --git a/src/base/utils/random.cpp b/src/base/utils/random.cpp
index b0b1e2d96..77d4a2dec 100644
--- a/src/base/utils/random.cpp
+++ b/src/base/utils/random.cpp
@@ -33,13 +33,12 @@
 #include <QtGlobal>
 
 #ifdef Q_OS_WIN
-#ifndef NOMINMAX
-#define NOMINMAX
-#endif
 #include <Windows.h>
 #include <Ntsecapi.h>
 #else  // Q_OS_WIN
+#include <cerrno>
 #include <cstdio>
+#include <cstring>
 #endif
 
 #include <QString>
@@ -97,7 +96,7 @@ namespace
             : m_randDev {fopen("/dev/urandom", "rb")}
         {
             if (!m_randDev)
-                qFatal("Failed to open /dev/urandom");
+                qFatal("Failed to open /dev/urandom. Reason: %s. Error code: %d.\n", std::strerror(errno), errno);
         }
 
         ~RandomLayer()
@@ -119,7 +118,7 @@ namespace
         {
             result_type buf = 0;
             if (fread(&buf, sizeof(buf), 1, m_randDev) != 1)
-                qFatal("Read /dev/urandom error");
+                qFatal("Read /dev/urandom error. Reason: %s. Error code: %d.\n", std::strerror(errno), errno);
 
             return buf;
         }