diff --git a/Library/Homebrew/software_spec.rb b/Library/Homebrew/software_spec.rb
index 88370e0fad..fe0277adb1 100644
--- a/Library/Homebrew/software_spec.rb
+++ b/Library/Homebrew/software_spec.rb
@@ -78,8 +78,8 @@ class SoftwareSpec
   def option name, description=nil
     name = 'c++11' if name == :cxx11
     name = name.to_s if Symbol === name
-    raise "Option name is required." if name.empty?
-    raise "Options should not start with dashes." if name[0, 1] == "-"
+    raise ArgumentError, "option name is required" if name.empty?
+    raise ArgumentError, "options should not start with dashes" if name.start_with?("-")
     build.add(name, description)
   end
 
diff --git a/Library/Homebrew/test/test_software_spec.rb b/Library/Homebrew/test/test_software_spec.rb
index db22420220..702d2c5819 100644
--- a/Library/Homebrew/test/test_software_spec.rb
+++ b/Library/Homebrew/test/test_software_spec.rb
@@ -48,11 +48,11 @@ class SoftwareSpecTests < Homebrew::TestCase
   end
 
   def test_option_raises_when_begins_with_dashes
-    assert_raises(RuntimeError) { @spec.option('--foo') }
+    assert_raises(ArgumentError) { @spec.option("--foo") }
   end
 
   def test_option_raises_when_name_empty
-    assert_raises(RuntimeError) { @spec.option('') }
+    assert_raises(ArgumentError) { @spec.option("") }
   end
 
   def test_option_accepts_symbols