diff --git a/lib/ruby_llm/error.rb b/lib/ruby_llm/error.rb
index 6768ab943..f182dfda1 100644
--- a/lib/ruby_llm/error.rb
+++ b/lib/ruby_llm/error.rb
@@ -69,7 +69,8 @@ class << self
         /token count exceeds/i,
         /input[_\s-]?token/i,
         /input or output tokens? must be reduced/i,
-        /reduce the length of messages/i
+        /reduce the length of messages/i,
+        /prompt is too long/i
       ].freeze
 
       def parse_error(provider:, response:) # rubocop:disable Metrics/PerceivedComplexity
diff --git a/spec/ruby_llm/error_middleware_spec.rb b/spec/ruby_llm/error_middleware_spec.rb
index 9437c9c79..ae957989a 100644
--- a/spec/ruby_llm/error_middleware_spec.rb
+++ b/spec/ruby_llm/error_middleware_spec.rb
@@ -58,6 +58,16 @@
       end.to raise_error(RubyLLM::ContextLengthExceededError)
     end
 
+    it "maps Anthropic's 'prompt is too long' 400 error to ContextLengthExceededError" do
+      msg = 'prompt is too long: 209025 tokens > 200000 maximum'
+      response = Struct.new(:status, :body).new(400, %({"error":{"message":"#{msg}"}}))
+      provider = instance_double(RubyLLM::Provider, parse_error: msg)
+
+      expect do
+        described_class.parse_error(provider: provider, response: response)
+      end.to raise_error(RubyLLM::ContextLengthExceededError)
+    end
+
     it 'keeps regular 400 errors as BadRequestError' do
       response = Struct.new(:status, :body).new(400, '{"error":{"message":"Invalid model specified"}}')
       provider = instance_double(RubyLLM::Provider, parse_error: 'Invalid model specified')