diff --git a/lib/rack/query_parser.rb b/lib/rack/query_parser.rb
index 388e083c7..cea6b9b09 100644
--- a/lib/rack/query_parser.rb
+++ b/lib/rack/query_parser.rb
@@ -32,12 +32,12 @@ def initialize(params_class, key_space_limit, param_depth_limit)
     # Parses a query string by breaking it up at the '&'.  You can also use this
     # to parse cookies by changing the characters used in the second parameter
     # (which defaults to '&').
-    def parse_query(qs, d = nil, &unescaper)
+    def parse_query(qs, separator = nil, &unescaper)
       unescaper ||= method(:unescape)
 
       params = make_params
 
-      (qs || '').split(d ? (COMMON_SEP[d] || /[#{d}] */n) : DEFAULT_SEP).each do |p|
+      (qs || '').split(separator ? (COMMON_SEP[separator] || /[#{separator}] */n) : DEFAULT_SEP).each do |p|
         next if p.empty?
         k, v = p.split('=', 2).map!(&unescaper)
 
@@ -60,11 +60,11 @@ def parse_query(qs, d = nil, &unescaper)
     # query strings with parameters of conflicting types, in this case a
     # ParameterTypeError is raised. Users are encouraged to return a 400 in this
     # case.
-    def parse_nested_query(qs, d = nil)
+    def parse_nested_query(qs, separator = nil)
       params = make_params
 
       unless qs.nil? || qs.empty?
-        (qs || '').split(d ? (COMMON_SEP[d] || /[#{d}] */n) : DEFAULT_SEP).each do |p|
+        (qs || '').split(separator ? (COMMON_SEP[separator] || /[#{separator}] */n) : DEFAULT_SEP).each do |p|
           k, v = p.split('=', 2).map! { |s| unescape(s) }
 
           normalize_params(params, k, v, param_depth_limit)