diff --git a/docs/README.md b/docs/README.md
index c5ef2b6..94b03ef 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -24,12 +24,12 @@ Each negotiator exposes two methods: [ANG::AbstractNegotiator#best][] and [ANG::
 negotiator = ANG.negotiator
 
 accept_header = "text/html, application/xhtml+xml, application/xml;q=0.9"
-priorities = ["text/html; charset=UTF-8", "application/json", "application/xml;q=0.5"]
+priorities = ["text/html; charset=utf-8", "application/json", "application/xml;q=0.5"]
 
 accept = negotiator.best(accept_header, priorities).not_nil!
 
 accept.media_range # => "text/html"
-accept.parameters  # => {"charset" => "UTF-8"}
+accept.parameters  # => {"charset" => "utf-8"}
 ```
 
 The [ANG::Negotiator][] type returns an [ANG::Accept][], or `nil` if negotiating the best media type has failed.
@@ -39,7 +39,7 @@ The [ANG::Negotiator][] type returns an [ANG::Accept][], or `nil` if negotiating
 ```crystal
 negotiator = ANG.charset_negotiator
 
-accept_header = "ISO-8859-1, UTF-8; q=0.9"
+accept_header = "ISO-8859-1, utf-8; q=0.9"
 priorities = ["iso-8859-1;q=0.3", "utf-8;q=0.9", "utf-16;q=1.0"]
 
 accept = negotiator.best(accept_header, priorities).not_nil!
diff --git a/spec/negotiator_spec.cr b/spec/negotiator_spec.cr
index f267d92..353942d 100644
--- a/spec/negotiator_spec.cr
+++ b/spec/negotiator_spec.cr
@@ -71,9 +71,9 @@ struct NegotiatorTest < NegotiatorTestCase
       {"image/png, text/plain, audio/ogg", {"baz/asdf"}, nil},
       {"image/png, text/plain, audio/ogg", {"audio/ogg"}, {"audio/ogg", nil}},
       {"image/png, text/plain, audio/ogg", {"YO/SuP"}, nil},
-      {"text/html; charset=UTF-8, application/pdf", {"text/html; charset=UTF-8"}, {"text/html", {"charset" => "UTF-8"}}},
-      {"text/html; charset=UTF-8, application/pdf", {"text/html"}, nil},
-      {"text/html, application/pdf", {"text/html; charset=UTF-8"}, {"text/html", {"charset" => "UTF-8"}}},
+      {"text/html; charset=utf-8, application/pdf", {"text/html; charset=utf-8"}, {"text/html", {"charset" => "utf-8"}}},
+      {"text/html; charset=utf-8, application/pdf", {"text/html"}, nil},
+      {"text/html, application/pdf", {"text/html; charset=utf-8"}, {"text/html", {"charset" => "utf-8"}}},
 
       # PHP"s PEAR HTTP2 assertions I took from the other lib.
       {php_pear_header, {"image/gif", "image/png", "application/xhtml+xml", "application/xml", "text/html", "image/jpeg", "text/plain"}, {"image/png", nil}},
diff --git a/src/abstract_negotiator.cr b/src/abstract_negotiator.cr
index 0f67a51..1bddf8c 100644
--- a/src/abstract_negotiator.cr
+++ b/src/abstract_negotiator.cr
@@ -26,9 +26,9 @@ abstract class Athena::Negotiation::AbstractNegotiator(HeaderType)
       raise ex if strict
     end
 
-    accepted_priorties = priorities.map { |p| HeaderType.new p }
+    accepted_priorities = priorities.map { |p| HeaderType.new p }
 
-    matches = self.find_matches accepted_headers, accepted_priorties
+    matches = self.find_matches accepted_headers, accepted_priorities
 
     specific_matches = matches.reduce({} of Int32 => ANG::AcceptMatch) do |acc, match|
       ANG::AcceptMatch.reduce acc, match
@@ -38,7 +38,7 @@ abstract class Athena::Negotiation::AbstractNegotiator(HeaderType)
 
     match = specific_matches.shift?
 
-    match.nil? ? nil : accepted_priorties[match.index]
+    match.nil? ? nil : accepted_priorities[match.index]
   end
 
   # Returns an array of `HeaderType` that the provided *header* allows, ordered so that the `#best` match is first.
diff --git a/src/accept.cr b/src/accept.cr
index 8a4b6df..d69e91a 100644
--- a/src/accept.cr
+++ b/src/accept.cr
@@ -3,11 +3,11 @@ require "./base_accept"
 # Represents an [Accept](https://tools.ietf.org/html/rfc7231#section-5.3.2) header media type.
 #
 # ```
-# accept = ANG::Accept.new "application/json; q = 0.75; charset = UTF-8"
+# accept = ANG::Accept.new "application/json; q = 0.75; charset = utf-8"
 #
-# accept.header            # => "application/json; q = 0.75; charset = UTF-8"
-# accept.normalized_header # => "application/json; charset=UTF-8"
-# accept.parameters        # => {"charset" => "UTF-8"}
+# accept.header            # => "application/json; q = 0.75; charset = utf-8"
+# accept.normalized_header # => "application/json; charset=utf-8"
+# accept.parameters        # => {"charset" => "utf-8"}
 # accept.quality           # => 0.75
 # accept.type              # => "application"
 # accept.sub_type          # => "json"
diff --git a/src/base_accept.cr b/src/base_accept.cr
index f11d50e..b9e02b8 100644
--- a/src/base_accept.cr
+++ b/src/base_accept.cr
@@ -10,7 +10,7 @@ abstract struct Athena::Negotiation::BaseAccept
   getter normalized_header : String
 
   # Returns any extension parameters included in the header `self` represents.
-  # E.x. `charset=UTF-8` or `version=2`.
+  # E.x. `charset=utf-8` or `version=2`.
   getter parameters : Hash(String, String) = Hash(String, String).new
 
   # Returns the [quality value](https://tools.ietf.org/html/rfc7231#section-5.3.1) of the header `self` represents.