"spec.author" is better for single-author gems.

"spec.author=" expects a String represents a single author.
"spec.authors=" expects an Array which is a list of multiple authors.

http://guides.rubygems.org/specification-reference/

doc/mrbgems/README.md

@@ -99,7 +99,7 @@ GEM directory. A typical GEM specification could look like this for example:
 
 	MRuby::Gem::Specification.new('c_and_ruby_extension_example') do |spec|
 	  spec.license = 'MIT'
-	  spec.authors = 'mruby developers'
+	  spec.author  = 'mruby developers'
 	end
 
 The mrbgems build process will use this specification to compile Object and Ruby
@@ -124,7 +124,7 @@ In case your GEM is depending on other GEMs please use
 
 	MRuby::Gem::Specification.new('c_and_ruby_extension_example') do |spec|
 	  spec.license = 'MIT'
-	  spec.authors = 'mruby developers'
+	  spec.author  = 'mruby developers'
 
 	  # add GEM dependency mruby-parser.
 	  # Version has to be between 1.0.0 and 1.5.2

examples/mrbgems/c_and_ruby_extension_example/mrbgem.rake

@@ -1,6 +1,6 @@
 MRuby::Gem::Specification.new('c_and_ruby_extension_example') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
  
   # Add compile flags
   # spec.cc.flags << ''

examples/mrbgems/c_extension_example/mrbgem.rake

@@ -1,6 +1,6 @@
 MRuby::Gem::Specification.new('c_extension_example') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
  
   # Add compile flags
   # spec.cc.flags << '-g'

examples/mrbgems/ruby_extension_example/mrbgem.rake

@@ -1,6 +1,6 @@
 MRuby::Gem::Specification.new('ruby_extension_example') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
  
   # Add compile flags
   # spec.cc.flags << ''

mrbgems/mruby-array-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-array-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-bin-mirb/mrbgem.rake

@@ -1,5 +1,5 @@
 MRuby::Gem::Specification.new('mruby-bin-mirb') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
   spec.bins = %w(mirb)
 end

mrbgems/mruby-bin-mruby/mrbgem.rake

@@ -1,5 +1,5 @@
 MRuby::Gem::Specification.new('mruby-bin-mruby') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
   spec.bins = %w(mruby)
 end

mrbgems/mruby-enum-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-enum-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-eval/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-eval') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-fiber/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-fiber') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-hash-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-hash-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-math/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-math') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-numeric-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-numeric-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-object-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-object-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-objectspace/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-objectspace') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-print/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-print') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-proc-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-proc-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-random/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-random') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-range-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-range-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-sprintf/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-sprintf') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-string-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-string-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-struct/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-struct') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-symbol-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-symbol-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-time/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-time') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end

mrbgems/mruby-toplevel-ext/mrbgem.rake

@@ -1,4 +1,4 @@
 MRuby::Gem::Specification.new('mruby-toplevel-ext') do |spec|
   spec.license = 'MIT'
-  spec.authors = 'mruby developers'
+  spec.author  = 'mruby developers'
 end