diff --git a/lib/rackstash/adapter.rb b/lib/rackstash/adapter.rb
index 6ffa6a7..7fb0a64 100644
--- a/lib/rackstash/adapter.rb
+++ b/lib/rackstash/adapter.rb
@@ -110,7 +110,9 @@ module Rackstash
         scheme = uri.scheme || uri.opaque
 
         return unless scheme
-        adapter_class = adapter_schemes.fetch(scheme.to_s.downcase) { return }
+        adapter_class = adapter_schemes.fetch(scheme.to_s.downcase) {
+          raise ArgumentError, "No log adapter found for URI #{uri}"
+        }
 
         if adapter_class.respond_to?(:from_uri)
           adapter_class.from_uri(uri)
diff --git a/spec/rackstash/adapter_spec.rb b/spec/rackstash/adapter_spec.rb
index c86bc32..6cff907 100644
--- a/spec/rackstash/adapter_spec.rb
+++ b/spec/rackstash/adapter_spec.rb
@@ -261,8 +261,9 @@ describe Rackstash::Adapter do
           unknown_uri = 'unknown://example.com'
 
           expect(adapter).to_not receive(:from_uri)
-          expect(adapter).to receive(:new).with(unknown_uri).and_call_original
-          expect(described_class[unknown_uri]).to be_an Rackstash::Adapter::BaseAdapter
+          expect(adapter).not_to receive(:new)
+          expect { described_class[unknown_uri] }
+            .to raise_error ArgumentError, "No log adapter found for URI unknown://example.com"
         end
       end
     end