diff --git a/lib/rubygems/commands/build_command.rb b/lib/rubygems/commands/build_command.rb
index eaf8573d8fa8..84faef2b82e4 100644
--- a/lib/rubygems/commands/build_command.rb
+++ b/lib/rubygems/commands/build_command.rb
@@ -79,7 +79,7 @@ def find_gemspec
   end
 
   def build_gem(gem_name)
-    gemspec = File.exist?(gem_name) ? gem_name : "#{gem_name}.gemspec"
+    gemspec = File.extname(gem_name) == ".gemspec" ? gem_name : "#{gem_name}.gemspec"
 
     if File.exist?(gemspec)
       spec = Gem::Specification.load(gemspec)
diff --git a/test/rubygems/test_gem_commands_build_command.rb b/test/rubygems/test_gem_commands_build_command.rb
index 37c3c120a52c..954f035406b3 100644
--- a/test/rubygems/test_gem_commands_build_command.rb
+++ b/test/rubygems/test_gem_commands_build_command.rb
@@ -273,7 +273,7 @@ def test_execute_outside_dir
   end
 
   def test_can_find_gemspecs_without_dot_gemspec
-    gemspec_file = File.join(@tempdir, @gem.spec_name)
+    gemspec_file = File.join(@tempdir, @gem.name)
 
     File.open gemspec_file + ".gemspec", 'w' do |gs|
       gs.write @gem.to_ruby