1 files changed, 4 insertions, 2 deletions
diff --git a/ext/ripper/extconf.rb b/ext/ripper/extconf.rb
index 6a793b8699..2dde565bd9 100644
--- a/ext/ripper/extconf.rb
+++ b/ext/ripper/extconf.rb
@@ -5,7 +5,9 @@ require 'mkmf'
 require 'rbconfig'
 
 def main
-  unless find_executable(ENV["YACC"] || 'bison')
+  yacc = ENV["YACC"] || "bison"
+
+  unless find_executable(yacc)
     unless File.exist?('ripper.c') or File.exist?("#{$srcdir}/ripper.c")
       raise 'missing bison; abort'
     end
@@ -17,7 +19,7 @@ def main
   $VPATH << '$(topdir)' << '$(top_srcdir)'
   $INCFLAGS << ' -I$(topdir) -I$(top_srcdir)'
   create_makefile 'ripper' do |conf|
-    conf << "BISON = #{ENV['YACC'] || 'bison'}"
+    conf << "BISON = #{yacc}"
   end
 end