diff --git a/docs/changelog.txt b/docs/changelog.txt
index 3c6ede53a4..05c030023c 100644
--- a/docs/changelog.txt
+++ b/docs/changelog.txt
@@ -133,6 +133,7 @@ Template for new versions:
 
 ## Lua
 - Added ``dfhack.maps.forEachTile`` to scan a cuboid of tiles with a declarative filter and apply actions (count, set tiletype or per-tiletype replacements, set designation/occupancy fields, spawn constructions, Lua callback) in a single native call
+- ``widgets.Slider`` and ``widgets.RangeSlider``: fix sliders allowing values outside their number of stops (``num_stops``) when clicked or dragged with the mouse
 - Fixed ``ipairs()`` on enum attribute tables (e.g. ``df.item_type.attrs``) never terminating (issue #1860)
 - Added ``dfhack.maps.getTileBlockCoord``, ``dfhack.maps.getBlockOrigin``, and ``dfhack.maps.getTileBlockOffset`` to convert between tile and block coordinates
 
diff --git a/library/lua/gui/widgets/range_slider.lua b/library/lua/gui/widgets/range_slider.lua
index 9b44e0fd54..0f53906c8c 100644
--- a/library/lua/gui/widgets/range_slider.lua
+++ b/library/lua/gui/widgets/range_slider.lua
@@ -1,4 +1,4 @@
-local core = require('gui.widgets.slide_core')
+local _SliderCore = require('gui.widgets.slide_core')
 
 --------------------------------
 -- RangeSlider
@@ -16,11 +16,11 @@ local core = require('gui.widgets.slide_core')
 ---@class widgets.RangeSlider.initTable: widgets.RangeSlider.attrs
 ---@field num_stops integer
 
----@class widgets.RangeSlider: widgets.Widget, widgets.RangeSlider.attrs
----@field super widgets.Widget
+---@class widgets.RangeSlider: widgets._SliderCore, widgets.RangeSlider.attrs
+---@field super widgets._SliderCore
 ---@field ATTRS widgets.RangeSlider.attrs|fun(attributes: widgets.RangeSlider.attrs.partial)
 ---@overload fun(init_table: widgets.RangeSlider.initTable): self
-RangeSlider = defclass(RangeSlider, slide_core)
+RangeSlider = defclass(RangeSlider, _SliderCore)
 RangeSlider.ATTRS{
     get_left_idx_fn=DEFAULT_NIL,
     get_right_idx_fn=DEFAULT_NIL,
@@ -44,7 +44,7 @@ function RangeSlider:onInput(keys)
     local left_pos = width_per_idx*(left_idx-1)
     local right_pos = width_per_idx*(right_idx-1) + 4
     if x < left_pos then
-        self.on_left_change(self.get_left_idx_fn() - 1)
+        self.on_left_change(self:clamp_idx(self.get_left_idx_fn() - 1))
     elseif x < left_pos+3 then
         self.is_dragging_target = 'left'
         self.is_dragging_idx = x - left_pos
@@ -55,7 +55,7 @@ function RangeSlider:onInput(keys)
         self.is_dragging_target = 'right'
         self.is_dragging_idx = x - right_pos
     else
-        self.on_right_change(self.get_right_idx_fn() + 1)
+        self.on_right_change(self:clamp_idx(self.get_right_idx_fn() + 1))
     end
     return true
 end
diff --git a/library/lua/gui/widgets/slide_core.lua b/library/lua/gui/widgets/slide_core.lua
index 450954b9c1..84ef12427a 100644
--- a/library/lua/gui/widgets/slide_core.lua
+++ b/library/lua/gui/widgets/slide_core.lua
@@ -3,46 +3,50 @@ local Widget = require('gui.widgets.widget')
 local to_pen = dfhack.pen.parse
 
 --------------------------------
--- slide_core
+-- _SliderCore
 --------------------------------
 
----@class widgets.slide_core.attrs: widgets.Widget.attrs
+---@class widgets._SliderCore.attrs: widgets.Widget.attrs
 ---@field num_stops integer
 ---@field is_single boolean
 ---@field w integer
 
----@class widgets.slide_core.attrs.partial: widgets.slide_core.attrs
+---@class widgets._SliderCore.attrs.partial: widgets._SliderCore.attrs
 
----@class widgets.slide_core.initTable: widgets.slide_core.attrs
+---@class widgets._SliderCore.initTable: widgets._SliderCore.attrs
 ---@field num_stops integer
 
----@class widgets.slide_core: widgets.Widget, widgets.slide_core.attrs
+---@class widgets._SliderCore: widgets.Widget, widgets._SliderCore.attrs
 ---@field super widgets.Widget
----@field ATTRS widgets.slide_core.attrs|fun(attributes: widgets.slide_core.attrs.partial)
----@overload fun(init_table: widgets.slide_core.initTable): self
-slide_core = defclass(slide_core, Widget)
-slide_core.ATTRS{
+---@field ATTRS widgets._SliderCore.attrs|fun(attributes: widgets._SliderCore.attrs.partial)
+---@overload fun(init_table: widgets._SliderCore.initTable): self
+_SliderCore = defclass(_SliderCore, Widget)
+_SliderCore.ATTRS{
     num_stops=DEFAULT_NIL,
     is_single=DEFAULT_NIL,
     w=DEFAULT_NIL
 }
 
-function slide_core:preinit(init_table)
+function _SliderCore:preinit(init_table)
     init_table.frame = init_table.frame or {}
     init_table.frame.h = init_table.frame.h or 1
 end
 
-function slide_core:init()
+function _SliderCore:init()
     local min_stops = self:get_min_stops()
     if self.num_stops < min_stops then error(('too few stops, expected at least %s'):format(min_stops)) end
     self.is_dragging_target = nil -- 'left', 'right', or 'both'
     self.is_dragging_idx = nil -- offset from leftmost dragged tile
 end
 
-function slide_core:get_min_stops()
+function _SliderCore:get_min_stops()
     return self.is_single and 1 or 2
 end
 
+function _SliderCore:clamp_idx(idx)
+    return math.max(1, math.min(self.num_stops, idx))
+end
+
 local function do_drag(self, width_per_idx)
     local x = self.frame_body:localXY(dfhack.screen.getMousePos())
     local cur_pos = x - self.is_dragging_idx
@@ -50,6 +54,7 @@ local function do_drag(self, width_per_idx)
     cur_pos = math.min(width_per_idx*(self.num_stops-1)+7, cur_pos)
     local offset = self.is_dragging_target == 'right' and -2 or 1
     local new_idx = math.max(0, cur_pos+offset)//width_per_idx + 1
+    new_idx = self:clamp_idx(new_idx)
     local new_left_idx, new_right_idx
     if self.is_dragging_target == 'right' then
         new_right_idx = new_idx
@@ -96,7 +101,7 @@ local SLIDER_TAB_LEFT = to_pen{ch=60, fg=COLOR_BLACK, bg=COLOR_YELLOW}
 local SLIDER_TAB_CENTER = to_pen{ch=9, fg=COLOR_BLACK, bg=COLOR_YELLOW}
 local SLIDER_TAB_RIGHT = to_pen{ch=62, fg=COLOR_BLACK, bg=COLOR_YELLOW}
 
-function slide_core:onRenderBody(dc, rect)
+function _SliderCore:onRenderBody(dc, rect)
     local left_idx, right_idx
     if self.get_idx_fn ~= nil then
         left_idx = self.get_idx_fn()
@@ -160,4 +165,4 @@ function slide_core:onRenderBody(dc, rect)
     end
 end
 
-return slide_core
+return _SliderCore
diff --git a/library/lua/gui/widgets/slider.lua b/library/lua/gui/widgets/slider.lua
index 65ce28a5c7..480f4787f8 100644
--- a/library/lua/gui/widgets/slider.lua
+++ b/library/lua/gui/widgets/slider.lua
@@ -1,4 +1,4 @@
-local core = require('gui.widgets.slide_core')
+local _SliderCore = require('gui.widgets.slide_core')
 
 --------------------------------
 -- Slider
@@ -15,11 +15,11 @@ local core = require('gui.widgets.slide_core')
 ---@class widgets.Slider.initTable: widgets.Slider.attrs
 ---@field num_stops integer
 
----@class widgets.Slider: widgets.Widget, widgets.Slider.attrs
----@field super widgets.Widget
+---@class widgets.Slider: widgets._SliderCore, widgets.Slider.attrs
+---@field super widgets._SliderCore
 ---@field ATTRS widgets.Slider.attrs|fun(attributes: widgets.Slider.attrs.partial)
 ---@overload fun(init_table: widgets.Slider.initTable): self
-Slider = defclass(Slider, slide_core)
+Slider = defclass(Slider, _SliderCore)
 Slider.ATTRS{
     get_idx_fn=DEFAULT_NIL,
     on_change=DEFAULT_NIL,
@@ -41,7 +41,7 @@ function Slider:onInput(keys)
     local left_pos = width_per_idx*(left_idx-1)
     local right_pos = width_per_idx*(right_idx-1) + 4
     if x < left_pos then
-        self.on_change(self.get_idx_fn() - 1)
+        self.on_change(self:clamp_idx(self.get_idx_fn() - 1))
     elseif x < left_pos+3 then
         self.is_dragging_target = 'left'
         self.is_dragging_idx = x - left_pos
@@ -52,7 +52,7 @@ function Slider:onInput(keys)
         self.is_dragging_target = 'right'
         self.is_dragging_idx = x - right_pos
     else
-        self.on_change(self.get_idx_fn() + 1)
+        self.on_change(self:clamp_idx(self.get_idx_fn() + 1))
     end
     return true
 end