diff --git a/4chan_x.coffee b/4chan_x.coffee
index 7f9f96c46..10812dc67 100644
--- a/4chan_x.coffee
+++ b/4chan_x.coffee
@@ -426,7 +426,20 @@ keyModeInsert = (e) ->
         remove $ '#qr'
         e.preventDefault()
     else if e.ctrlKey and char is "S"
-        console.log 'spoiler'
+        ta = document.activeElement
+        return unless ta.nodeName is 'TEXTAREA'
+
+        value    = ta.value
+        selStart = ta.selectionStart
+        selEnd   = ta.selectionEnd
+
+        valStart = value[0...selStart] + '[spoiler]'
+        valMid   = value[selStart...selEnd]
+        valEnd   = '[/spoiler]' + value[selEnd..]
+
+        ta.value = valStart + valMid + valEnd
+        range = valStart.length + valMid.length
+        ta.setSelectionRange range, range
         e.preventDefault()
 
 keyModeNormal = (e) ->
diff --git a/4chan_x.js b/4chan_x.js
index 5d3917cdb..f436968ae 100644
--- a/4chan_x.js
+++ b/4chan_x.js
@@ -536,14 +536,26 @@
     }
   };
   keyModeInsert = function(e) {
-    var char, kc;
+    var char, kc, range, selEnd, selStart, ta, valEnd, valMid, valStart, value;
     kc = g.keyCode;
     char = g.char;
     if (kc === 27) {
       remove($('#qr'));
       return e.preventDefault();
     } else if (e.ctrlKey && char === "S") {
-      console.log('spoiler');
+      ta = document.activeElement;
+      if (ta.nodeName !== 'TEXTAREA') {
+        return;
+      }
+      value = ta.value;
+      selStart = ta.selectionStart;
+      selEnd = ta.selectionEnd;
+      valStart = value.slice(0, selStart) + '[spoiler]';
+      valMid = value.slice(selStart, selEnd);
+      valEnd = '[/spoiler]' + value.slice(selEnd);
+      ta.value = valStart + valMid + valEnd;
+      range = valStart.length + valMid.length;
+      ta.setSelectionRange(range, range);
       return e.preventDefault();
     }
   };