diff --git a/test/http/charsets.rb b/test/http/charsets.rb
index c86010c..4912db4 100644
--- a/test/http/charsets.rb
+++ b/test/http/charsets.rb
@@ -51,6 +51,10 @@
 		expect(charsets[1].charset).to be == "iso-8859-1"
 		expect(charsets[2].charset).to be == "windows-1252"
 	end
+
+	it "should accept empty string" do
+		expect(HTTP::Accept::Charsets.parse("")).to be == []
+	end
 	
 	it "should not accept invalid input" do
 		[
@@ -60,6 +64,10 @@
 			expect{HTTP::Accept::Charsets.parse(text)}.to raise_exception(HTTP::Accept::ParseError)
 		end
 	end
+
+	it "should not accept nil input" do
+		expect{HTTP::Accept::Charsets.parse(nil)}.to raise_exception(TypeError)
+	end
 	
 	describe "browser_preferred_charsets" do
 		it "should parse a non-blank header" do
diff --git a/test/http/encodings.rb b/test/http/encodings.rb
index 1a9540a..5261e44 100644
--- a/test/http/encodings.rb
+++ b/test/http/encodings.rb
@@ -52,6 +52,10 @@
 		expect(encodings[2].encoding).to be == "deflate"
 	end
 	
+	it "should accept empty string" do
+		expect(HTTP::Accept::Encodings.parse("")).to be == []
+	end
+
 	it "should not accept invalid input" do
 		[
 			"gzip;f=1", "br;gzip",
@@ -60,6 +64,10 @@
 			expect{HTTP::Accept::Encodings.parse(text)}.to raise_exception(HTTP::Accept::ParseError)
 		end
 	end
+
+	it "should not accept nil input" do
+		expect{HTTP::Accept::Encodings.parse(nil)}.to raise_exception(TypeError)
+	end
 	
 	describe "browser_preferred_content_codings" do
 		it "should parse a non-blank header" do
diff --git a/test/http/media_types.rb b/test/http/media_types.rb
index c7a7d98..822c12e 100644
--- a/test/http/media_types.rb
+++ b/test/http/media_types.rb
@@ -33,6 +33,10 @@
 		expect(media_types[0].mime_type).to be == "foo/bar"
 		expect(media_types[0].parameters).to be == {'key' => "A,B,C"}
 	end
+
+	it "should accept empty string" do
+		expect(HTTP::Accept::MediaTypes.parse("")).to be == []
+	end
 	
 	it "should not accept invalid input" do
 		[
@@ -50,6 +54,10 @@
 			expect{HTTP::Accept::MediaTypes.parse(text)}.to raise_exception(HTTP::Accept::ParseError)
 		end
 	end
+
+	it "should not accept nil input" do
+		expect{HTTP::Accept::MediaTypes.parse(nil)}.to raise_exception(TypeError)
+	end
 end
 
 AMediaTypeSelector = Sus::Shared("a media type selector") do |header_value, priorities = nil|