diff --git a/src/slic3r/GUI/Jobs/BoostThreadWorker.cpp b/src/slic3r/GUI/Jobs/BoostThreadWorker.cpp
index a6eee28ac..8475f0537 100644
--- a/src/slic3r/GUI/Jobs/BoostThreadWorker.cpp
+++ b/src/slic3r/GUI/Jobs/BoostThreadWorker.cpp
@@ -6,10 +6,10 @@ namespace Slic3r { namespace GUI {
 
 void BoostThreadWorker::WorkerMessage::deliver(BoostThreadWorker &runner)
 {
-    switch(MsgType(m_data.index())) {
+    switch(MsgType(get_type())) {
     case Empty: break;
     case Status: {
-        StatusInfo info = std::get<Status>(m_data);
+        auto info = boost::get<StatusInfo>(m_data);
         if (runner.get_pri()) {
             runner.get_pri()->set_progress(info.status);
             runner.get_pri()->set_status_text(info.msg.c_str());
@@ -17,7 +17,7 @@ void BoostThreadWorker::WorkerMessage::deliver(BoostThreadWorker &runner)
         break;
     }
     case Finalize: {
-        JobEntry& entry = std::get<Finalize>(m_data);
+        auto& entry = boost::get<JobEntry>(m_data);
         entry.job->finalize(entry.canceled, entry.eptr);
 
         // Unhandled exceptions are rethrown without mercy.
@@ -27,7 +27,7 @@ void BoostThreadWorker::WorkerMessage::deliver(BoostThreadWorker &runner)
         break;
     }
     case MainThreadCall: {
-        MainThreadCallData &calldata = std::get<MainThreadCall>(m_data);
+        auto &calldata = boost::get<MainThreadCallData >(m_data);
         calldata.fn();
         calldata.promise.set_value();
 
diff --git a/src/slic3r/GUI/Jobs/BoostThreadWorker.hpp b/src/slic3r/GUI/Jobs/BoostThreadWorker.hpp
index 1775a90bd..908ebbb05 100644
--- a/src/slic3r/GUI/Jobs/BoostThreadWorker.hpp
+++ b/src/slic3r/GUI/Jobs/BoostThreadWorker.hpp
@@ -1,7 +1,7 @@
 #ifndef BOOSTTHREADWORKER_HPP
 #define BOOSTTHREADWORKER_HPP
 
-#include <variant>
+#include <boost/variant.hpp>
 
 #include "Worker.hpp"
 
@@ -40,10 +40,12 @@ class BoostThreadWorker : public Worker, private Job::Ctl
         std::promise<void>    promise;
     };
 
+    struct EmptyMessage {};
+
     class WorkerMessage
     {
         enum MsgType { Empty, Status, Finalize, MainThreadCall };
-        std::variant<std::monostate, StatusInfo, JobEntry, MainThreadCallData> m_data;
+        boost::variant<EmptyMessage, StatusInfo, JobEntry, MainThreadCallData> m_data;
 
     public:
         WorkerMessage() = default;
@@ -53,7 +55,7 @@ class BoostThreadWorker : public Worker, private Job::Ctl
         WorkerMessage(JobEntry &&entry) : m_data{std::move(entry)} {}
         WorkerMessage(MainThreadCallData fn) : m_data{std::move(fn)} {}
 
-        int get_type () const { return m_data.index(); }
+        int get_type () const { return m_data.which(); }
 
         void deliver(BoostThreadWorker &runner);
     };