diff --git a/lib/csv.rb b/lib/csv.rb
index 509e978..9bb1830 100644
--- a/lib/csv.rb
+++ b/lib/csv.rb
@@ -1854,7 +1854,7 @@ def shift
       parts.each do |part|
         if in_extended_col
           # If we are continuing a previous column
-          if part[-1] == @quote_char && part.count(@quote_char) % 2 != 0
+          if part.end_with?(@quote_char) && part.count(@quote_char) % 2 != 0
             # extended column ends
             csv.last << part[0..-2]
             if csv.last =~ @parsers[:stray_quote]
@@ -1867,14 +1867,14 @@ def shift
             csv.last << part
             csv.last << @col_sep
           end
-        elsif part[0] == @quote_char
+        elsif part.start_with?(@quote_char)
           # If we are starting a new quoted column
           if part.count(@quote_char) % 2 != 0
             # start an extended column
             csv             << part[1..-1]
             csv.last        << @col_sep
             in_extended_col =  true
-          elsif part[-1] == @quote_char
+          elsif part.end_with?(@quote_char)
             # regular quoted column
             csv << part[1..-2]
             if csv.last =~ @parsers[:stray_quote]