diff --git a/lib/rexml/parsers/baseparser.rb b/lib/rexml/parsers/baseparser.rb
index c79de0eb..c01b087b 100644
--- a/lib/rexml/parsers/baseparser.rb
+++ b/lib/rexml/parsers/baseparser.rb
@@ -210,6 +210,8 @@ def pull_event
         return @stack.shift if @stack.size > 0
         #STDERR.puts @source.encoding
         #STDERR.puts "BUFFER = #{@source.buffer.inspect}"
+
+        @source.ensure_buffer
         if @document_status == nil
           start_position = @source.position
           if @source.match("<?", true)
@@ -236,6 +238,7 @@ def pull_event
               elsif @source.match(/\s*>/um, true)
                 id = [nil, nil, nil]
                 @document_status = :after_doctype
+                @source.ensure_buffer
               else
                 id = parse_id(base_error_message,
                               accept_external_id: true,
@@ -248,6 +251,7 @@ def pull_event
                   @document_status = :in_doctype
                 elsif @source.match(/\s*>/um, true)
                   @document_status = :after_doctype
+                  @source.ensure_buffer
                 else
                   message = "#{base_error_message}: garbage after external ID"
                   raise REXML::ParseException.new(message, @source)
@@ -646,6 +650,7 @@ def parse_attributes(prefixes, curr_ns)
               raise REXML::ParseException.new(message, @source)
             end
             unless scanner.scan(/.*#{Regexp.escape(quote)}/um)
+              @source.ensure_buffer
               match_data = @source.match(/^(.*?)(\/)?>/um, true)
               if match_data
                 scanner << "/" if closed
diff --git a/lib/rexml/source.rb b/lib/rexml/source.rb
index 81d96451..7f47c2be 100644
--- a/lib/rexml/source.rb
+++ b/lib/rexml/source.rb
@@ -68,6 +68,9 @@ def encoding=(enc)
     def read
     end
 
+    def ensure_buffer
+    end
+
     def match(pattern, cons=false)
       if cons
         @scanner.scan(pattern).nil? ? nil : @scanner
@@ -165,11 +168,14 @@ def read
       end
     end
 
+    def ensure_buffer
+      read if @scanner.eos? && @source
+    end
+
     # Note: When specifying a string for 'pattern', it must not include '>' except in the following formats:
     # - ">"
     # - "XXX>" (X is any string excluding '>')
     def match( pattern, cons=false )
-      read if @scanner.eos? && @source
       while true
         if cons
           md = @scanner.scan(pattern)