diff --git a/lib/devin_api/endpoints/session.rb b/lib/devin_api/endpoints/session.rb
index 892ffd8..137b9eb 100644
--- a/lib/devin_api/endpoints/session.rb
+++ b/lib/devin_api/endpoints/session.rb
@@ -21,7 +21,7 @@ def get_session(session_id)
       # @option params [String] :message The message to send (required)
       # @return [Hash] Response body
       def send_message(session_id, params = {})
-        post("/v1/session/#{session_id}/messages", params)
+        post("/v1/session/#{session_id}/message", params)
       end
 
       # Update session tags
diff --git a/lib/devin_api/resources/session.rb b/lib/devin_api/resources/session.rb
index 368a4f4..b222f18 100644
--- a/lib/devin_api/resources/session.rb
+++ b/lib/devin_api/resources/session.rb
@@ -15,7 +15,7 @@ def path
       end
 
       def send_message(message)
-        client.post("#{path}/messages", { message: message })
+        client.post("#{path}/message", { message: message })
       end
 
       def update_tags(tags)
diff --git a/spec/core/endpoints/session_spec.rb b/spec/core/endpoints/session_spec.rb
index ddb9e73..aeb34e3 100644
--- a/spec/core/endpoints/session_spec.rb
+++ b/spec/core/endpoints/session_spec.rb
@@ -37,7 +37,7 @@
 
   describe '#send_message' do
     before do
-      stub_request(:post, 'https://api.example.com/v1/session/devin-xxx/messages')
+      stub_request(:post, 'https://api.example.com/v1/session/devin-xxx/message')
         .with(
           body: { message: 'Can you explain this code?' }.to_json,
           headers: { 'Content-Type' => 'application/json' }
diff --git a/spec/core/endpoints/sessions_spec.rb b/spec/core/endpoints/sessions_spec.rb
index 8ddc6eb..4d81796 100644
--- a/spec/core/endpoints/sessions_spec.rb
+++ b/spec/core/endpoints/sessions_spec.rb
@@ -108,7 +108,7 @@
 
   describe '#send_message' do
     before do
-      stub_request(:post, 'https://api.example.com/v1/session/devin-xxx/messages')
+      stub_request(:post, 'https://api.example.com/v1/session/devin-xxx/message')
         .with(
           body: { message: 'Can you explain this code?' }.to_json,
           headers: { 'Content-Type' => 'application/json' }