diff --git a/lib/rackstash/adapter.rb b/lib/rackstash/adapter.rb
index 7fb0a64..c3a508a 100644
--- a/lib/rackstash/adapter.rb
+++ b/lib/rackstash/adapter.rb
@@ -53,7 +53,7 @@ module Rackstash
           case matcher
           when String
             matcher = matcher.to_s
-            if matcher =~ /\A[a-z0-9]+\z/
+            if matcher =~ /\A[a-z0-9]/
               # If the matcher is a lower-case string, we assume it is a URL
               # scheme.
               adapter_schemes[matcher.downcase] = adapter_class
diff --git a/spec/rackstash/adapter_spec.rb b/spec/rackstash/adapter_spec.rb
index 6cff907..84a8a99 100644
--- a/spec/rackstash/adapter_spec.rb
+++ b/spec/rackstash/adapter_spec.rb
@@ -210,6 +210,7 @@ describe Rackstash::Adapter do
     context 'with a registered scheme' do
       before do
         described_class.register adapter, 'dummy'
+        described_class.register adapter, 'foo+dummy'
       end
 
       it 'creates an adapter from the scheme' do
@@ -218,6 +219,12 @@ describe Rackstash::Adapter do
         expect(described_class[raw_uri]).to be_an Rackstash::Adapter::BaseAdapter
       end
 
+      it 'can use a complex scheme' do
+        raw_uri = 'foo+dummy://example.com'
+        expect(adapter).to receive(:from_uri).with(URI(raw_uri)).and_call_original
+        expect(described_class[raw_uri]).to be_an Rackstash::Adapter::BaseAdapter
+      end
+
       it 'calls adapter.new if adapter.from_uri is not available' do
         plain_adapter = Class.new(Rackstash::Adapter::BaseAdapter)
         described_class.register plain_adapter, 'dummy'