diff --git a/lib/ruby_algebra/polynomial.rb b/lib/ruby_algebra/polynomial.rb
index 1ddf2a9..5d5faa6 100644
--- a/lib/ruby_algebra/polynomial.rb
+++ b/lib/ruby_algebra/polynomial.rb
@@ -203,7 +203,7 @@ module RubyAlgebra
     end
 
     def to_s
-      result = coeff.to_s
+      result = @coeff != 1 ? @coeff.to_s : ''
       unless @variables.empty?
         first = true
         @variables.each do |var, power|