diff --git a/lib/thor/shell/basic.rb b/lib/thor/shell/basic.rb
index 71ce4071..bf1b89ef 100644
--- a/lib/thor/shell/basic.rb
+++ b/lib/thor/shell/basic.rb
@@ -377,11 +377,7 @@ def merge(destination, content) #:nodoc:
       end
 
       def merge_tool #:nodoc:
-        @merge_tool ||= ENV["THOR_MERGE"] || git_merge_tool
-      end
-
-      def git_merge_tool #:nodoc:
-        `git config merge.tool`.rstrip rescue ""
+        @merge_tool ||= ENV["THOR_MERGE"] || "git difftool --no-index"
       end
     end
   end