fix #1367

core/src/gui/main_window.cpp

@@ -576,6 +576,8 @@ void MainWindow::draw() {
         // Handle scrollwheel
         int wheel = ImGui::GetIO().MouseWheel;
         if (wheel != 0 && (gui::waterfall.mouseInFFT || gui::waterfall.mouseInWaterfall)) {
+            double nfreq;
+            if (vfo != NULL) {
                 // Select factor depending on modifier keys
                 double interval;
                 if (ImGui::IsKeyDown(ImGuiKey_LeftShift)) {
@@ -588,8 +590,6 @@ void MainWindow::draw() {
                     interval = vfo->snapInterval;
                 }
 
-            double nfreq;
-            if (vfo != NULL) {
                 nfreq = gui::waterfall.getCenterFrequency() + vfo->generalOffset + (interval * wheel);
                 nfreq = roundl(nfreq / interval) * interval;
             }