diff --git a/lib/redmine/scm/adapters/mercurial_adapter.rb b/lib/redmine/scm/adapters/mercurial_adapter.rb
index 77f7d015c..bbc4a2d61 100644
--- a/lib/redmine/scm/adapters/mercurial_adapter.rb
+++ b/lib/redmine/scm/adapters/mercurial_adapter.rb
@@ -164,7 +164,7 @@ module Redmine
               return []
             end
           end
-          cmd = "#{HG_BIN} -R #{target('')} diff --nodates --git #{diff_args}"
+          cmd = "#{HG_BIN} -R #{target('')} --config diff.git=false diff --nodates #{diff_args}"
           cmd << " -I #{target(path)}" unless path.empty?
           shellout(cmd) do |io|
             io.each_line do |line|
diff --git a/test/unit/lib/redmine/scm/adapters/mercurial_adapter_test.rb b/test/unit/lib/redmine/scm/adapters/mercurial_adapter_test.rb
index ed68eeaa8..24862681a 100644
--- a/test/unit/lib/redmine/scm/adapters/mercurial_adapter_test.rb
+++ b/test/unit/lib/redmine/scm/adapters/mercurial_adapter_test.rb
@@ -58,8 +58,8 @@ begin
           end
           [4, 'def6d2f1254a'].each do |r2|
             diff2 = @adapter.diff(nil,r1,r2)
-            assert_equal 50, diff2.size
-            buf =  diff2[42].gsub(/\r\n|\r|\n/, "")
+            assert_equal 49, diff2.size
+            buf =  diff2[41].gsub(/\r\n|\r|\n/, "")
             assert_equal "+class WelcomeController < ApplicationController", buf
             diff3 = @adapter.diff('sources/watchers_controller.rb', r1, r2)
             assert_equal 20, diff3.size