diff --git a/lib/rexml/parsers/baseparser.rb b/lib/rexml/parsers/baseparser.rb
index 8fe287a7..0b48ec14 100644
--- a/lib/rexml/parsers/baseparser.rb
+++ b/lib/rexml/parsers/baseparser.rb
@@ -158,6 +158,9 @@ module Private
           DEFAULT_ENTITIES_PATTERNS[term] = /&#{term};/
         end
         XML_PREFIXED_NAMESPACE = "http://www.w3.org/XML/1998/namespace"
+        EXTERNAL_ID_PUBLIC_PATTERN = /\s+#{PUBIDLITERAL}\s+#{SYSTEMLITERAL}/um
+        EXTERNAL_ID_SYSTEM_PATTERN  = /\s+#{SYSTEMLITERAL}/um
+        PUBLIC_ID_PATTERN = /\s+#{PUBIDLITERAL}/um
       end
       private_constant :Private
 
@@ -307,7 +310,6 @@ def pull_event
                 @source.ensure_buffer
               else
                 id = parse_id(base_error_message,
-                              accept_external_id: true,
                               accept_public_id: false)
                 if id[0] == "SYSTEM"
                   # For backward compatibility
@@ -409,7 +411,6 @@ def pull_event
               end
               name = parse_name(base_error_message)
               id = parse_id(base_error_message,
-                            accept_external_id: true,
                             accept_public_id: true)
               @source.skip_spaces
               unless @source.match?(">", true)
@@ -667,68 +668,41 @@ def parse_name(base_error_message)
       end
 
       def parse_id(base_error_message,
-                   accept_external_id:,
                    accept_public_id:)
-        if accept_external_id and (md = @source.match(EXTERNAL_ID_PUBLIC, true))
-          pubid = system = nil
-          pubid_literal = md[1]
-          pubid = pubid_literal[1..-2] if pubid_literal # Remove quote
-          system_literal = md[2]
-          system = system_literal[1..-2] if system_literal # Remove quote
-          ["PUBLIC", pubid, system]
-        elsif accept_public_id and (md = @source.match(PUBLIC_ID, true))
-          pubid = system = nil
-          pubid_literal = md[1]
-          pubid = pubid_literal[1..-2] if pubid_literal # Remove quote
-          ["PUBLIC", pubid, nil]
-        elsif accept_external_id and (md = @source.match(EXTERNAL_ID_SYSTEM, true))
-          system = nil
-          system_literal = md[1]
-          system = system_literal[1..-2] if system_literal # Remove quote
-          ["SYSTEM", nil, system]
-        else
-          details = parse_id_invalid_details(accept_external_id: accept_external_id,
-                                             accept_public_id: accept_public_id)
-          message = "#{base_error_message}: #{details}"
-          raise REXML::ParseException.new(message, @source)
-        end
-      end
-
-      def parse_id_invalid_details(accept_external_id:,
-                                   accept_public_id:)
-        public = /\A\s*PUBLIC/um
-        system = /\A\s*SYSTEM/um
-        if (accept_external_id or accept_public_id) and @source.match?(/#{public}/um)
-          if @source.match?(/#{public}(?:\s+[^'"]|\s*[\[>])/um)
-            return "public ID literal is missing"
-          end
-          unless @source.match?(/#{public}\s+#{PUBIDLITERAL}/um)
-            return "invalid public ID literal"
-          end
-          if accept_public_id
-            if @source.match?(/#{public}\s+#{PUBIDLITERAL}\s+[^'"]/um)
-              return "system ID literal is missing"
-            end
-            unless @source.match?(/#{public}\s+#{PUBIDLITERAL}\s+#{SYSTEMLITERAL}/um)
-              return "invalid system literal"
-            end
-            "garbage after system literal"
+        @source.skip_spaces
+        if @source.match?("PUBLIC", true)
+          if (md = @source.match(Private::EXTERNAL_ID_PUBLIC_PATTERN, true))
+            pubid = system = nil
+            pubid_literal = md[1]
+            pubid = pubid_literal[1..-2] if pubid_literal # Remove quote
+            system_literal = md[2]
+            system = system_literal[1..-2] if system_literal # Remove quote
+            ["PUBLIC", pubid, system]
+          elsif accept_public_id and (md = @source.match(Private::PUBLIC_ID_PATTERN, true))
+            pubid = system = nil
+            pubid_literal = md[1]
+            pubid = pubid_literal[1..-2] if pubid_literal # Remove quote
+            ["PUBLIC", pubid, nil]
+          elsif @source.match?(/(?:\s+[^'"]|\s*[\[>])/um)
+            raise REXML::ParseException.new("#{base_error_message}: public ID literal is missing", @source)
+          elsif !@source.match?(Private::PUBLIC_ID_PATTERN)
+            raise REXML::ParseException.new("#{base_error_message}: invalid public ID literal", @source)
           else
-            "garbage after public ID literal"
+            raise REXML::ParseException.new("#{base_error_message}: garbage after public ID literal", @source)
           end
-        elsif accept_external_id and @source.match?(/#{system}/um)
-          if @source.match?(/#{system}(?:\s+[^'"]|\s*[\[>])/um)
-            return "system literal is missing"
-          end
-          unless @source.match?(/#{system}\s+#{SYSTEMLITERAL}/um)
-            return "invalid system literal"
+        elsif @source.match?("SYSTEM", true)
+          if (md = @source.match(Private::EXTERNAL_ID_SYSTEM_PATTERN, true))
+            system = nil
+            system_literal = md[1]
+            system = system_literal[1..-2] if system_literal # Remove quote
+            ["SYSTEM", nil, system]
+          elsif @source.match?(/(?:\s+[^'"]|\s*[\[>])/um)
+            raise REXML::ParseException.new("#{base_error_message}: system literal is missing", @source)
+          else
+            raise REXML::ParseException.new("#{base_error_message}: invalid system literal", @source)
           end
-          "garbage after system literal"
         else
-          unless @source.match?(/\A\s*(?:PUBLIC|SYSTEM)\s/um)
-            return "invalid ID type"
-          end
-          "ID type is missing"
+          raise REXML::ParseException.new("#{base_error_message}: invalid ID type", @source)
         end
       end
 
diff --git a/test/parse/test_document_type_declaration.rb b/test/parse/test_document_type_declaration.rb
index d4658b9e..cc37ad3f 100644
--- a/test/parse/test_document_type_declaration.rb
+++ b/test/parse/test_document_type_declaration.rb
@@ -153,7 +153,22 @@ def test_no_literal
 Line: 3
 Position: 26
 Last 80 unconsumed characters:
-SYSTEM>  <r/> 
+>  <r/> 
+          DETAIL
+        end
+
+        def test_garbage_invalid_system_literal
+          exception = assert_raise(REXML::ParseException) do
+            parse(<<-DOCTYPE)
+<!DOCTYPE r SYSTEM '
+            DOCTYPE
+          end
+          assert_equal(<<-DETAIL.chomp, exception.to_s)
+Malformed DOCTYPE: invalid system literal
+Line: 3
+Position: 27
+Last 80 unconsumed characters:
+ '  <r/> 
           DETAIL
         end
 
@@ -165,10 +180,10 @@ def test_garbage_after_literal
           end
           assert_equal(<<-DETAIL.chomp, exception.to_s)
 Malformed DOCTYPE: garbage after external ID
-Line: 3
-Position: 36
+Line: 1
+Position: 29
 Last 80 unconsumed characters:
-x'>  <r/> 
+x'>
           DETAIL
         end
 
@@ -200,7 +215,7 @@ def test_content_double_quote
 Line: 3
 Position: 62
 Last 80 unconsumed characters:
-PUBLIC 'double quote " is invalid' "r.dtd">  <r/> 
+ 'double quote " is invalid' "r.dtd">  <r/> 
             DETAIL
           end
 
@@ -220,6 +235,21 @@ def test_double_quote
         end
 
         class TestSystemLiteral < self
+          def test_garbage_after_public_ID_literal
+            exception = assert_raise(REXML::ParseException) do
+              parse(<<-DOCTYPE)
+<!DOCTYPE r PUBLIC "public-id-literal" 'system>
+              DOCTYPE
+            end
+            assert_equal(<<-DETAIL.chomp, exception.to_s)
+Malformed DOCTYPE: garbage after public ID literal
+Line: 3
+Position: 54
+Last 80 unconsumed characters:
+ "public-id-literal" 'system>  <r/> 
+            DETAIL
+          end
+
           def test_garbage_after_literal
             exception = assert_raise(REXML::ParseException) do
               parse(<<-DOCTYPE)
diff --git a/test/parse/test_notation_declaration.rb b/test/parse/test_notation_declaration.rb
index 9e81b6a4..11914d37 100644
--- a/test/parse/test_notation_declaration.rb
+++ b/test/parse/test_notation_declaration.rb
@@ -32,10 +32,10 @@ def test_no_name
         end
         assert_equal(<<-DETAIL.chomp, exception.to_s)
 Malformed notation declaration: name is missing
-Line: 5
-Position: 72
+Line: 2
+Position: 62
 Last 80 unconsumed characters:
-<!NOTATION>  ]> <r/> 
+<!NOTATION>
         DETAIL
       end
 
@@ -62,10 +62,10 @@ def test_no_id_type
         end
         assert_equal(<<-DETAIL.chomp, exception.to_s)
 Malformed notation declaration: invalid ID type
-Line: 5
-Position: 77
+Line: 2
+Position: 67
 Last 80 unconsumed characters:
->  ]> <r/> 
+>
         DETAIL
       end
 
@@ -77,10 +77,10 @@ def test_invalid_id_type
         end
         assert_equal(<<-DETAIL.chomp, exception.to_s)
 Malformed notation declaration: invalid ID type
-Line: 5
-Position: 85
+Line: 2
+Position: 75
 Last 80 unconsumed characters:
- INVALID>  ]> <r/> 
+INVALID>
         DETAIL
       end
     end
@@ -98,7 +98,7 @@ def test_no_literal
 Line: 5
 Position: 84
 Last 80 unconsumed characters:
- SYSTEM>  ]> <r/> 
+>  ]> <r/> 
           DETAIL
         end
 
@@ -110,10 +110,10 @@ def test_garbage_after_literal
           end
           assert_equal(<<-DETAIL.chomp, exception.to_s)
 Malformed notation declaration: garbage before end >
-Line: 5
-Position: 103
+Line: 2
+Position: 93
 Last 80 unconsumed characters:
-x'>  ]> <r/> 
+x'>
           DETAIL
         end
 
@@ -145,7 +145,7 @@ def test_content_double_quote
 Line: 5
 Position: 129
 Last 80 unconsumed characters:
- PUBLIC 'double quote " is invalid' "system-literal">  ]> <r/> 
+ 'double quote " is invalid' "system-literal">  ]> <r/> 
             DETAIL
           end
 
@@ -173,10 +173,10 @@ def test_garbage_after_literal
             end
             assert_equal(<<-DETAIL.chomp, exception.to_s)
 Malformed notation declaration: garbage before end >
-Line: 5
-Position: 123
+Line: 2
+Position: 113
 Last 80 unconsumed characters:
-x'>  ]> <r/> 
+x'>
            DETAIL
           end
 
@@ -229,7 +229,7 @@ def test_no_literal
 Line: 5
 Position: 84
 Last 80 unconsumed characters:
- PUBLIC>  ]> <r/> 
+>  ]> <r/> 
         DETAIL
       end
 
@@ -244,7 +244,7 @@ def test_literal_content_double_quote
 Line: 5
 Position: 128
 Last 80 unconsumed characters:
- PUBLIC 'double quote \" is invalid in PubidLiteral'>  ]> <r/> 
+ 'double quote \" is invalid in PubidLiteral'>  ]> <r/> 
         DETAIL
       end