diff --git a/modules/lib/d3.keybinding.js b/modules/lib/d3.keybinding.js
index cc98ab242..7c9ec918a 100644
--- a/modules/lib/d3.keybinding.js
+++ b/modules/lib/d3.keybinding.js
@@ -169,7 +169,8 @@ d3keybinding.keyCodes = {
     '=': 187, 'equals': 187,
     // Comma, or ,
     ',': 188, comma: 188,
-    'dash': 189, //???
+    // Dash / Underscore key
+    'dash': 189,
     // Period, or ., or full-stop
     '.': 190, period: 190, 'full-stop': 190,
     // Slash, or /, or forward-slash
diff --git a/modules/ui/zoom.js b/modules/ui/zoom.js
index 685671d93..e8065d581 100644
--- a/modules/ui/zoom.js
+++ b/modules/ui/zoom.js
@@ -75,7 +75,7 @@ export function uiZoom(context) {
             keybinding.on([key, '⇧' + key], zoomIn);
             keybinding.on([uiCmd('⌘' + key), uiCmd('⌘⇧' + key)], zoomInFurther);
         });
-        _.each(['-','ffminus','_','dash'], function(key) {
+        _.each(['-','ffminus','dash'], function(key) {
             keybinding.on([key, '⇧' + key], zoomOut);
             keybinding.on([uiCmd('⌘' + key), uiCmd('⌘⇧' + key)], zoomOutFurther);
         });