diff --git a/lib/uri/common.rb b/lib/uri/common.rb
index 2bb13ad..26b179a 100644
--- a/lib/uri/common.rb
+++ b/lib/uri/common.rb
@@ -91,8 +91,8 @@ def self.for(scheme, *arguments, default: Generic)
     const_name = scheme.to_s.upcase
 
     uri_class = INITIAL_SCHEMES[const_name]
-    if !uri_class && !const_name.empty? && Schemes.const_defined?(const_name, false)
-      uri_class = Schemes.const_get(const_name, false)
+    uri_class ||= if /\A[A-Z]\w*\z/.match?(const_name) && Schemes.const_defined?(const_name, false)
+      Schemes.const_get(const_name, false)
     end
     uri_class ||= default
 
diff --git a/test/uri/test_generic.rb b/test/uri/test_generic.rb
index d122587..fdb405e 100644
--- a/test/uri/test_generic.rb
+++ b/test/uri/test_generic.rb
@@ -159,6 +159,13 @@ def test_parse
     assert_equal(nil, url.userinfo)
   end
 
+  def test_parse_scheme_with_symbols
+    # Valid schemes from https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml
+    assert_equal 'ms-search', URI.parse('ms-search://localhost').scheme
+    assert_equal 'microsoft.windows.camera', URI.parse('microsoft.windows.camera://localhost').scheme
+    assert_equal 'coaps+ws', URI.parse('coaps+ws:localhost').scheme
+  end
+
   def test_merge
     u1 = URI.parse('http://foo')
     u2 = URI.parse('http://foo/')