diff --git a/src/qpython.cpp b/src/qpython.cpp
index 7e99c18..e5c97ce 100644
--- a/src/qpython.cpp
+++ b/src/qpython.cpp
@@ -298,15 +298,10 @@ QPython::evaluate(QString expr)
     return convertPyObjectToQVariant(o.borrow());
 }
 
-void
-QPython::call(QVariant func, QVariant args, QJSValue callback)
+QVariantList
+QPython::unboxArgList(QVariant &args)
 {
-    QJSValue *cb = 0;
-    if (!callback.isNull() && !callback.isUndefined() && callback.isCallable()) {
-        cb = new QJSValue(callback);
-    }
-    // Unbox QJSValue from QVariant, since QJSValue::toVariant() can cause calls into
-    // QML engine and we don't want that to happen from non-GUI thread
+    // Unbox QJSValue from QVariant
     QVariantList vl = args.toList();
     for (int i = 0, c = vl.count(); i < c; ++i) {
         QVariant &v = vl[i];
@@ -315,11 +310,31 @@ QPython::call(QVariant func, QVariant args, QJSValue callback)
             v = v.value<QJSValue>().toVariant();
         }
     }
-    emit process(func, vl, cb);
+    return vl;
+}
+
+void
+QPython::call(QVariant func, QVariant boxed_args, QJSValue callback)
+{
+    QJSValue *cb = 0;
+    if (!callback.isNull() && !callback.isUndefined() && callback.isCallable()) {
+        cb = new QJSValue(callback);
+    }
+    // Unbox QJSValue from QVariant, since QJSValue::toVariant() can cause calls into
+    // QML engine and we don't want that to happen from non-GUI thread
+    QVariantList unboxed_args = unboxArgList(boxed_args);
+
+    emit process(func, unboxed_args, cb);
 }
 
 QVariant
-QPython::call_sync(QVariant func, QVariant args)
+QPython::call_sync(QVariant func, QVariant boxed_args)
+{
+    return call_internal(func, boxed_args, true);
+}
+
+QVariant
+QPython::call_internal(QVariant func, QVariant args, bool unbox)
 {
     ENSURE_GIL_STATE;
 
@@ -348,8 +363,18 @@ QPython::call_sync(QVariant func, QVariant args)
         return QVariant();
     }
 
+    // Unbox QJSValue from QVariant if requested. QPython::call may have done
+    // this already, but call_sync is also exposed directly, so it does not
+    // happen in this case otherwise
+    QVariant args_unboxed;
+    if (unbox) {
+        args_unboxed = unboxArgList(args);
+    } else {
+        args_unboxed = args;
+    }
+
     QVariant v;
-    QString errorMessage = priv->call(callable.borrow(), name, args, &v);
+    QString errorMessage = priv->call(callable.borrow(), name, args_unboxed, &v);
     if (!errorMessage.isNull()) {
         emitError(errorMessage);
     }
diff --git a/src/qpython.h b/src/qpython.h
index 46e751f..5d8ad8c 100644
--- a/src/qpython.h
+++ b/src/qpython.h
@@ -297,7 +297,11 @@ class QPython : public QObject {
          * \result The return value of the Python call as Qt data type
          **/
         Q_INVOKABLE QVariant
-        call_sync(QVariant func, QVariant args=QVariantList());
+        call_sync(QVariant func, QVariant boxed_args=QVariantList());
+
+        QVariant
+        call_internal(QVariant func, QVariant boxed_args=QVariantList(),
+            bool unbox=true);
 
         /**
          * \brief Get an attribute value of a Python object synchronously
@@ -361,7 +365,7 @@ class QPython : public QObject {
         void error(QString traceback);
 
         /* For internal use only */
-        void process(QVariant func, QVariant args, QJSValue *callback);
+        void process(QVariant func, QVariant unboxed_args, QJSValue *callback);
         void import(QString name, QJSValue *callback);
         void import_names(QString name, QVariant args, QJSValue *callback);
 
@@ -375,6 +379,8 @@ class QPython : public QObject {
         void disconnectNotify(const QMetaMethod &signal);
 
     private:
+        QVariantList unboxArgList(QVariant &args);
+
         static QPythonPriv *priv;
 
         QPythonWorker *worker;
diff --git a/src/qpython_worker.cpp b/src/qpython_worker.cpp
index dbb4e50..abbf454 100644
--- a/src/qpython_worker.cpp
+++ b/src/qpython_worker.cpp
@@ -32,9 +32,9 @@ QPythonWorker::~QPythonWorker()
 }
 
 void
-QPythonWorker::process(QVariant func, QVariant args, QJSValue *callback)
+QPythonWorker::process(QVariant func, QVariant unboxed_args, QJSValue *callback)
 {
-    QVariant result = qpython->call_sync(func, args);
+    QVariant result = qpython->call_internal(func, unboxed_args, false);
     if (callback) {
         emit finished(result, callback);
     }
diff --git a/src/qpython_worker.h b/src/qpython_worker.h
index 2bacb2d..d540c1a 100644
--- a/src/qpython_worker.h
+++ b/src/qpython_worker.h
@@ -34,7 +34,7 @@ class QPythonWorker : public QObject {
         ~QPythonWorker();
 
     public slots:
-        void process(QVariant func, QVariant args, QJSValue *callback);
+        void process(QVariant func, QVariant unboxed_args, QJSValue *callback);
         void import(QString func, QJSValue *callback);
         void import_names(QString func, QVariant args, QJSValue *callback);