diff --git a/Library/Homebrew/service.rb b/Library/Homebrew/service.rb
index 1447935bfd0cd..297705f103777 100644
--- a/Library/Homebrew/service.rb
+++ b/Library/Homebrew/service.rb
@@ -55,7 +55,7 @@ def root_dir(path = nil)
       when String, Pathname
         @root_dir = path.to_s
       else
-        raise TypeError, "Service#root_dir expects a String"
+        raise TypeError, "Service#root_dir expects a String or Pathname"
       end
     end
 
@@ -67,7 +67,7 @@ def input_path(path = nil)
       when String, Pathname
         @input_path = path.to_s
       else
-        raise TypeError, "Service#input_path expects a String"
+        raise TypeError, "Service#input_path expects a String or Pathname"
       end
     end