diff --git a/app/assets/javascripts/app/lib/base/jquery.textmodule.js b/app/assets/javascripts/app/lib/base/jquery.textmodule.js
index 718fe7c5d..37f4a38c7 100644
--- a/app/assets/javascripts/app/lib/base/jquery.textmodule.js
+++ b/app/assets/javascripts/app/lib/base/jquery.textmodule.js
@@ -163,8 +163,11 @@
       e.keyCode = e.which = keyCode;
     }
 
-    // shift
-    if (e.keyCode === 16) return
+    // ignore invalid key codes if search is opened (issue #3637)
+    if (this.isActive() && e.keyCode === undefined) return
+
+    // skip on shift + arrow_keys
+    if (_.contains([16, 37, 38, 39, 40], e.keyCode)) return
 
     // enter
     if (e.keyCode === 13) {
@@ -172,9 +175,6 @@
       return
     }
 
-    // arrow keys
-    if (e.keyCode === 37 || e.keyCode === 38 || e.keyCode === 39 || e.keyCode === 40) return
-
     var newChar = String.fromCharCode(e.which)
 
     // observe other keys
diff --git a/spec/system/examples/text_modules_examples.rb b/spec/system/examples/text_modules_examples.rb
index d61e86597..7d2640eba 100644
--- a/spec/system/examples/text_modules_examples.rb
+++ b/spec/system/examples/text_modules_examples.rb
@@ -30,6 +30,16 @@ RSpec.shared_examples 'text modules' do |path:|
     end
   end
 
+  it 'does not break search on backspace' do
+    visit path
+    within(:active_content) do
+      find('select[name="group_id"]').select(1)
+      find(:richtext).send_keys('@@agen')
+      find(:richtext).send_keys(:backspace)
+      expect(page).to have_no_text('No results found')
+    end
+  end
+
   it 'supports group-dependent text modules' do
 
     # give user access to all groups including those created