diff --git a/app/javascript/mastodon/reducers/compose.js b/app/javascript/mastodon/reducers/compose.js
index d7478c33d..edc277433 100644
--- a/app/javascript/mastodon/reducers/compose.js
+++ b/app/javascript/mastodon/reducers/compose.js
@@ -184,11 +184,12 @@ const ignoreSuggestion = (state, position, token, completion, path) => {
 };
 
 const sortHashtagsByUse = (state, tags) => {
-  const personalHistory = state.get('tagHistory');
+  const personalHistory = state.get('tagHistory').map(tag => tag.toLowerCase());
 
-  return tags.sort((a, b) => {
-    const usedA = personalHistory.includes(a.name);
-    const usedB = personalHistory.includes(b.name);
+  const tagsWithLowercase = tags.map(t => ({ ...t, lowerName: t.name.toLowerCase() }));
+  const sorted = tagsWithLowercase.sort((a, b) => {
+    const usedA = personalHistory.includes(a.lowerName);
+    const usedB = personalHistory.includes(b.lowerName);
 
     if (usedA === usedB) {
       return 0;
@@ -198,6 +199,8 @@ const sortHashtagsByUse = (state, tags) => {
       return 1;
     }
   });
+  sorted.forEach(tag => delete tag.lowerName);
+  return sorted;
 };
 
 const insertEmoji = (state, position, emojiData, needsSpace) => {