diff --git a/lib/search.rb b/lib/search.rb
index 3ffbda872f..07ddba622e 100644
--- a/lib/search.rb
+++ b/lib/search.rb
@@ -399,8 +399,17 @@ class Search
 
     if slug[1]
       # sub category
-      parent_category_id = Category.where(slug: slug[0].downcase, parent_category_id: nil).pluck(:id).first
-      category_id = Category.where(slug: slug[1].downcase, parent_category_id: parent_category_id).pluck(:id).first
+      parent_category_id = Category
+        .where("lower(slug) = ? AND parent_category_id IS NULL", slug[0].downcase)
+        .pluck(:id)
+        .first
+
+      category_id = Category
+        .where("lower(slug) = ? AND parent_category_id = ?",
+          slug[1].downcase, parent_category_id
+        )
+        .pluck(:id)
+        .first
     else
       # main category
       if slug[0][0] == "="
@@ -409,7 +418,7 @@ class Search
         exact = false
       end
 
-      category_id = Category.where(slug: slug[0].downcase)
+      category_id = Category.where("lower(slug) = ?", slug[0].downcase)
         .order('case when parent_category_id is null then 0 else 1 end')
         .pluck(:id)
         .first
diff --git a/spec/components/search_spec.rb b/spec/components/search_spec.rb
index 993a259719..287fa8e7f6 100644
--- a/spec/components/search_spec.rb
+++ b/spec/components/search_spec.rb
@@ -873,25 +873,28 @@ describe Search do
 
     it 'supports category slug and tags' do
       # main category
-      category = Fabricate(:category, name: 'category 24', slug: 'category-24')
+      category = Fabricate(:category, name: 'category 24', slug: 'cateGory-24')
       topic = Fabricate(:topic, created_at: 3.months.ago, category: category)
       post = Fabricate(:post, raw: 'Sams first post', topic: topic)
 
-      expect(Search.execute('sams post #category-24').posts.length).to eq(1)
+      expect(Search.execute('sams post #categoRy-24').posts.length).to eq(1)
       expect(Search.execute("sams post category:#{category.id}").posts.length).to eq(1)
-      expect(Search.execute('sams post #category-25').posts.length).to eq(0)
+      expect(Search.execute('sams post #categoRy-25').posts.length).to eq(0)
 
       sub_category = Fabricate(:category, name: 'sub category', slug: 'sub-category', parent_category_id: category.id)
       second_topic = Fabricate(:topic, created_at: 3.months.ago, category: sub_category)
       Fabricate(:post, raw: 'sams second post', topic: second_topic)
 
-      expect(Search.execute("sams post category:category-24").posts.length).to eq(2)
-      expect(Search.execute("sams post category:=category-24").posts.length).to eq(1)
+      expect(Search.execute("sams post category:categoRY-24").posts.length).to eq(2)
+      expect(Search.execute("sams post category:=cAtegory-24").posts.length).to eq(1)
 
       expect(Search.execute("sams post #category-24").posts.length).to eq(2)
       expect(Search.execute("sams post #=category-24").posts.length).to eq(1)
       expect(Search.execute("sams post #sub-category").posts.length).to eq(1)
 
+      expect(Search.execute("sams post #categoRY-24:SUB-category").posts.length)
+        .to eq(1)
+
       # tags
       topic.tags = [Fabricate(:tag, name: 'alpha'), Fabricate(:tag, name: 'привет'), Fabricate(:tag, name: 'HeLlO')]
       expect(Search.execute('this is a test #alpha').posts.map(&:id)).to eq([post.id])