diff --git a/src/music_gui.cpp b/src/music_gui.cpp
index 639f360ce0..4f9e5b978d 100644
--- a/src/music_gui.cpp
+++ b/src/music_gui.cpp
@@ -826,7 +826,7 @@ struct MusicWindow : public Window {
 
 			case WID_M_MUSIC_VOL: case WID_M_EFFECT_VOL: { // volume sliders
 				uint8_t &vol = (widget == WID_M_MUSIC_VOL) ? _settings_client.music.music_vol : _settings_client.music.effect_vol;
-				if (ClickSliderWidget(this->GetWidget<NWidgetBase>(widget)->GetCurrentRect(), pt, 0, INT8_MAX, vol)) {
+				if (ClickSliderWidget(this->GetWidget<NWidgetBase>(widget)->GetCurrentRect(), pt, 0, INT8_MAX, 0, vol)) {
 					if (widget == WID_M_MUSIC_VOL) {
 						MusicDriver::GetInstance()->SetVolume(vol);
 					} else {
diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index 889f65d7ad..3dfdccbb14 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -786,8 +786,7 @@ struct GameOptionsWindow : Window {
 #endif /* HAS_TRUETYPE_FONT */
 
 			case WID_GO_GUI_SCALE:
-				if (ClickSliderWidget(this->GetWidget<NWidgetBase>(widget)->GetCurrentRect(), pt, MIN_INTERFACE_SCALE, MAX_INTERFACE_SCALE, this->gui_scale)) {
-					if (!_ctrl_pressed) this->gui_scale = ((this->gui_scale + 12) / 25) * 25;
+				if (ClickSliderWidget(this->GetWidget<NWidgetBase>(widget)->GetCurrentRect(), pt, MIN_INTERFACE_SCALE, MAX_INTERFACE_SCALE, _ctrl_pressed ? 0 : SCALE_NMARKS, this->gui_scale)) {
 					this->SetWidgetDirty(widget);
 				}
 
@@ -822,7 +821,7 @@ struct GameOptionsWindow : Window {
 			case WID_GO_BASE_SFX_VOLUME:
 			case WID_GO_BASE_MUSIC_VOLUME: {
 				uint8_t &vol = (widget == WID_GO_BASE_MUSIC_VOLUME) ? _settings_client.music.music_vol : _settings_client.music.effect_vol;
-				if (ClickSliderWidget(this->GetWidget<NWidgetBase>(widget)->GetCurrentRect(), pt, 0, INT8_MAX, vol)) {
+				if (ClickSliderWidget(this->GetWidget<NWidgetBase>(widget)->GetCurrentRect(), pt, 0, INT8_MAX, 0, vol)) {
 					if (widget == WID_GO_BASE_MUSIC_VOLUME) {
 						MusicDriver::GetInstance()->SetVolume(vol);
 					} else {
diff --git a/src/slider.cpp b/src/slider.cpp
index c6f086c006..30e0591e83 100644
--- a/src/slider.cpp
+++ b/src/slider.cpp
@@ -82,10 +82,13 @@ void DrawSliderWidget(Rect r, int min_value, int max_value, int nmarks, int valu
  * Handle click on a slider widget to change the value
  * @param r      Rectangle of the widget
  * @param pt     Clicked point
+ * @param min_value Minimum value of slider
+ * @param max_value Maximum value of slider
+ * @param nmarks Number of marks displayed. Value will be rounded to nearest mark.
  * @param value[in,out] Value to modify
  * @return       True if the value setting was modified
  */
-bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, int &value)
+bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, int nmarks, int &value)
 {
 	max_value -= min_value;
 
@@ -94,6 +97,11 @@ bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, int &valu
 	if (_current_text_dir == TD_RTL) new_value = max_value - new_value;
 	new_value += min_value;
 
+	if (nmarks > 0) {
+		const int step = max_value / (nmarks - 1);
+		new_value = ((new_value + step / 2) / step) * step;
+	}
+
 	if (new_value != value) {
 		value = new_value;
 		return true;
diff --git a/src/slider_func.h b/src/slider_func.h
index f0ff9cc0ac..cb5b97fe06 100644
--- a/src/slider_func.h
+++ b/src/slider_func.h
@@ -15,12 +15,12 @@
 
 using SliderMarkFunc = StringID(int nmarks, int mark, int value);
 void DrawSliderWidget(Rect r, int min_value, int max_value, int nmarks, int value, SliderMarkFunc *mark_func);
-bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, int &value);
+bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, int nmarks, int &value);
 
-inline bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, uint8_t &value)
+inline bool ClickSliderWidget(Rect r, Point pt, int min_value, int max_value, int nmarks, uint8_t &value)
 {
 	int tmp_value = value;
-	if (!ClickSliderWidget(r, pt, min_value, max_value, tmp_value)) return false;
+	if (!ClickSliderWidget(r, pt, min_value, max_value, nmarks, tmp_value)) return false;
 	value = tmp_value;
 	return true;
 }