diff --git a/app/assets/javascripts/gfm_auto_complete.js b/app/assets/javascripts/gfm_auto_complete.js
index 77e6de5b0e21ffa6e671919ab1b76e55450ead94..6b4ed25178729d014241b40fe17349cec18ba8f6 100644
--- a/app/assets/javascripts/gfm_auto_complete.js
+++ b/app/assets/javascripts/gfm_auto_complete.js
@@ -700,8 +700,8 @@ class GfmAutoComplete {
               // Do not match if there are two consecutive `~` characters (strikethrough) before the cursor
               return null;
             }
-            const lastCandidate = subtext.split(flag).pop();
-            if (labels.find((label) => label.title.startsWith(lastCandidate))) {
+            const lastCandidate = subtext.split(flag).pop().toLowerCase();
+            if (labels.find((label) => label.title.toLowerCase().startsWith(lastCandidate))) {
               return lastCandidate;
             }
           }
diff --git a/spec/features/issues/gfm_autocomplete_spec.rb b/spec/features/issues/gfm_autocomplete_spec.rb
index 9f0259d45fd95e7960f4243a00f65145a3dc2e49..e0f28d7c108bd840bf4c9c2c98ffca9719bf7251 100644
--- a/spec/features/issues/gfm_autocomplete_spec.rb
+++ b/spec/features/issues/gfm_autocomplete_spec.rb
@@ -300,7 +300,7 @@
       end
 
       it 'allows spaces when autocompleting multi-word labels' do
-        fill_in 'Comment', with: '~Accepting merge'
+        fill_in 'Comment', with: '~accepting merge'
 
         wait_for_requests