diff --git a/config/locales/server.en.yml b/config/locales/server.en.yml
index 6226fa5cdef..7b968b3914a 100644
--- a/config/locales/server.en.yml
+++ b/config/locales/server.en.yml
@@ -2411,7 +2411,7 @@ en:
         <tr><td><code>status:open</code></td><td><code>status:closed</code></td><td><code>status:archived</code></td><td><code>status:noreplies</code></td><td><code>status:singleuser</code></td></tr>
         <tr><td><code>category:foo</code></td><td><code>user:foo</code></td><td colspan=3></td></tr>
         <tr><td><code>in:likes</code></td><td><code>in:posted</code></td><td><code>in:watching</code></td><td><code>in:tracking</code></td><td><code>in:private</code></td></tr>
-        <tr><td><code>in:bookmarks</code><td colspan=4></td></tr>
+        <tr><td><code>in:bookmarks</code></td><td><code>in:first</code></td><td colspan=3></td></tr>
         <tr><td><code>posts_count:num</code></td><td><code>min_age:days</code></td><td><code>max_age:days</code></td> <td colspan=2></td></tr>
         </table>
       </p>
diff --git a/lib/search.rb b/lib/search.rb
index 7c02b5a1603..b5883a49d50 100644
--- a/lib/search.rb
+++ b/lib/search.rb
@@ -179,6 +179,9 @@ class Search
     posts.where("topics.posts_count = ?", match.to_i)
   end
 
+  advanced_filter(/in:first/) do |posts|
+    posts.where("posts.post_number = 1")
+  end
 
   advanced_filter(/in:(likes|bookmarks)/) do |posts, match|
     if @guardian.user
diff --git a/spec/components/search_spec.rb b/spec/components/search_spec.rb
index 82638fbf36f..1ded92fbc77 100644
--- a/spec/components/search_spec.rb
+++ b/spec/components/search_spec.rb
@@ -373,15 +373,20 @@ describe Search do
 
   describe 'Advanced search' do
 
-    it 'supports min_age and max_age' do
+    it 'supports min_age and max_age in:first' do
       topic = Fabricate(:topic, created_at: 3.months.ago)
       Fabricate(:post, raw: 'hi this is a test 123 123', topic: topic)
+      Fabricate(:post, raw: 'boom boom shake the room', topic: topic)
 
       expect(Search.execute('test min_age:100').posts.length).to eq(1)
       expect(Search.execute('test min_age:10').posts.length).to eq(0)
       expect(Search.execute('test max_age:10').posts.length).to eq(1)
       expect(Search.execute('test max_age:100').posts.length).to eq(0)
 
+      expect(Search.execute('test in:first').posts.length).to eq(1)
+      expect(Search.execute('boom').posts.length).to eq(1)
+      expect(Search.execute('boom in:first').posts.length).to eq(0)
+
     end
 
     it 'can find by status' do