diff --git a/dotdrop/comparator.py b/dotdrop/comparator.py
index 7cab104..8cd86cb 100644
--- a/dotdrop/comparator.py
+++ b/dotdrop/comparator.py
@@ -15,12 +15,12 @@ from dotdrop.utils import must_ignore, uniq_list, diff
 
 class Comparator:
 
-    def __init__(self, diffopts='', debug=False):
+    def __init__(self, diff_cmd='', debug=False):
         """constructor
-        @diffopts: switches to pass to unix diff
+        @diff_cmd: diff command to use
         @debug: enable debug
         """
-        self.diffopts = diffopts
+        self.diff_cmd = diff_cmd
         self.debug = debug
         self.log = Logger()
 
@@ -122,9 +122,9 @@ class Comparator:
         return ''.join(ret)
 
     def _diff(self, left, right, header=False):
-        """diff using the unix tool diff"""
+        """diff two files"""
         out = diff(modified=left, original=right, raw=False,
-                   opts=self.diffopts, debug=self.debug)
+                   diff_cmd=self.diff_cmd, debug=self.debug)
         if header:
             lshort = os.path.basename(left)
             out = '=> diff \"{}\":\n{}'.format(lshort, out)
diff --git a/dotdrop/dotdrop.py b/dotdrop/dotdrop.py
index 3dbe377..57efdf9 100644
--- a/dotdrop/dotdrop.py
+++ b/dotdrop/dotdrop.py
@@ -96,7 +96,8 @@ def cmd_install(o):
                      diff=o.install_diff, debug=o.debug,
                      totemp=tmpdir,
                      showdiff=o.install_showdiff,
-                     backup_suffix=o.install_backup_suffix)
+                     backup_suffix=o.install_backup_suffix,
+                     diff_cmd=o.diff_command)
     installed = 0
     tvars = t.add_tmp_vars()
 
@@ -211,8 +212,9 @@ def cmd_compare(o, tmp):
     inst = Installer(create=o.create, backup=o.backup,
                      dry=o.dry, base=o.dotpath,
                      workdir=o.workdir, debug=o.debug,
-                     backup_suffix=o.install_backup_suffix)
-    comp = Comparator(diffopts=o.compare_dopts, debug=o.debug)
+                     backup_suffix=o.install_backup_suffix,
+                     diff_cmd=o.diff_command)
+    comp = Comparator(diff_cmd=o.diff_command, debug=o.debug)
 
     for dotfile in selected:
         if o.debug:
@@ -362,7 +364,7 @@ def cmd_importer(o):
         if os.path.exists(srcf):
             overwrite = True
             if o.safe:
-                c = Comparator(debug=o.debug)
+                c = Comparator(debug=o.debug, diff_cmd=o.diff_command)
                 diff = c.compare(srcf, dst)
                 if diff != '':
                     # files are different, dunno what to do
diff --git a/dotdrop/installer.py b/dotdrop/installer.py
index 2c5936a..c61cf98 100644
--- a/dotdrop/installer.py
+++ b/dotdrop/installer.py
@@ -19,7 +19,7 @@ class Installer:
     def __init__(self, base='.', create=True, backup=True,
                  dry=False, safe=False, workdir='~/.config/dotdrop',
                  debug=False, diff=True, totemp=None, showdiff=False,
-                 backup_suffix='.dotdropbak'):
+                 backup_suffix='.dotdropbak', diff_cmd=''):
         """constructor
         @base: directory path where to search for templates
         @create: create directory hierarchy if missing when installing
@@ -32,6 +32,7 @@ class Installer:
         @totemp: deploy to this path instead of dotfile dst if not None
         @showdiff: show the diff before overwriting (or asking for)
         @backup_suffix: suffix for dotfile backup file
+        @diff_cmd: diff command to use
         """
         self.create = create
         self.backup = backup
@@ -44,6 +45,7 @@ class Installer:
         self.totemp = totemp
         self.showdiff = showdiff
         self.backup_suffix = backup_suffix
+        self.diff_cmd = diff_cmd
         self.comparing = False
         self.action_executed = False
         self.log = Logger()
@@ -437,7 +439,8 @@ class Installer:
         if content:
             tmp = utils.write_to_tmpfile(content)
             src = tmp
-        diff = utils.diff(modified=src, original=dst, raw=False)
+        diff = utils.diff(modified=src, original=dst, raw=False,
+                          diff_cmd=self.diff_cmd)
         if tmp:
             utils.remove(tmp, quiet=True)
 
diff --git a/dotdrop/options.py b/dotdrop/options.py
index 8489ca9..de7babc 100644
--- a/dotdrop/options.py
+++ b/dotdrop/options.py
@@ -55,7 +55,7 @@ Usage:
   dotdrop import    [-Vbdf]     [-c <path>] [-p <profile>]
                                 [-l <link>] <path>...
   dotdrop compare   [-Vb]       [-c <path>] [-p <profile>]
-                                [-o <opts>] [-C <file>...] [-i <pattern>...]
+                                [-C <file>...] [-i <pattern>...]
   dotdrop update    [-VbfdkP]   [-c <path>] [-p <profile>]
                                 [-i <pattern>...] [<path>...]
   dotdrop remove    [-Vbfdk]    [-c <path>] [-p <profile>] [<path>...]
@@ -70,7 +70,6 @@ Options:
   -c --cfg=<path>         Path to the config.
   -C --file=<path>        Path of dotfile to compare.
   -i --ignore=<pattern>   Pattern to ignore.
-  -o --dopts=<opts>       Diff options [default: ].
   -l --link=<link>        "link_on_import" (nolink|link|link_children).
   -n --nodiff             Do not diff when installing.
   -t --temp               Install to a temporary directory for review.
@@ -231,7 +230,6 @@ class Options(AttrMonitor):
                                              if a.kind == Action.post]
         self.install_ignore = self.instignore
         # "compare" specifics
-        self.compare_dopts = self.args['--dopts']
         self.compare_focus = self.args['--file']
         self.compare_ignore = self.args['--ignore']
         self.compare_ignore.extend(self.cmpignore)
diff --git a/dotdrop/settings.py b/dotdrop/settings.py
index e375163..bfc3ae6 100644
--- a/dotdrop/settings.py
+++ b/dotdrop/settings.py
@@ -33,6 +33,7 @@ class Settings(DictParser):
     key_minversion = 'minversion'
     key_func_file = 'func_file'
     key_filter_file = 'filter_file'
+    key_diff_command = 'diff_command'
 
     # import keys
     key_import_actions = 'import_actions'
@@ -47,7 +48,8 @@ class Settings(DictParser):
                  link_on_import=LinkTypes.NOLINK, longkey=False,
                  upignore=[], cmpignore=[], instignore=[],
                  workdir='~/.config/dotdrop', showdiff=False,
-                 minversion=None, func_file=[], filter_file=[]):
+                 minversion=None, func_file=[], filter_file=[],
+                 diff_command='diff -r {0} {1}'):
         self.backup = backup
         self.banner = banner
         self.create = create
@@ -69,6 +71,7 @@ class Settings(DictParser):
         self.minversion = minversion
         self.func_file = func_file
         self.filter_file = filter_file
+        self.diff_command = diff_command
 
     def _serialize_seq(self, name, dic):
         """serialize attribute 'name' into 'dic'"""
@@ -77,7 +80,6 @@ class Settings(DictParser):
 
     def serialize(self):
         """Return key-value pair representation of the settings"""
-        # Tedious, but less error-prone than introspection
         dic = {
             self.key_backup: self.backup,
             self.key_banner: self.banner,
@@ -91,6 +93,7 @@ class Settings(DictParser):
             self.key_showdiff: self.showdiff,
             self.key_workdir: self.workdir,
             self.key_minversion: self.minversion,
+            self.key_diff_command: self.diff_command,
         }
         self._serialize_seq(self.key_default_actions, dic)
         self._serialize_seq(self.key_import_actions, dic)
diff --git a/dotdrop/utils.py b/dotdrop/utils.py
index 893af71..1fae268 100644
--- a/dotdrop/utils.py
+++ b/dotdrop/utils.py
@@ -70,9 +70,12 @@ def shell(cmd, debug=False):
     return ret == 0, out
 
 
-def diff(original, modified, raw=True, opts='', debug=False):
-    """call unix diff to compare two files"""
-    cmd = 'diff -r {} \"{}\" \"{}\"'.format(opts, original, modified)
+def diff(original, modified, raw=True,
+         diff_cmd='diff -r {0} {1}', debug=False):
+    """compare two files"""
+    if not diff_cmd:
+        diff_cmd = 'diff -r {0} {1}'
+    cmd = diff_cmd.format(original, modified)
     _, out = run(shlex.split(cmd), raw=raw, debug=debug)
     return out
 
diff --git a/tests-ng/diff-cmd.sh b/tests-ng/diff-cmd.sh
new file mode 100755
index 0000000..1956c26
--- /dev/null
+++ b/tests-ng/diff-cmd.sh
@@ -0,0 +1,125 @@
+#!/usr/bin/env bash
+# author: deadc0de6 (https://github.com/deadc0de6)
+# Copyright (c) 2017, deadc0de6
+#
+# test diff cmd
+# returns 1 in case of error
+#
+
+# exit on first error
+#set -e
+
+# all this crap to get current path
+rl="readlink -f"
+if ! ${rl} "${0}" >/dev/null 2>&1; then
+  rl="realpath"
+
+  if ! hash ${rl}; then
+    echo "\"${rl}\" not found !" && exit 1
+  fi
+fi
+cur=$(dirname "$(${rl} "${0}")")
+
+#hash dotdrop >/dev/null 2>&1
+#[ "$?" != "0" ] && echo "install dotdrop to run tests" && exit 1
+
+#echo "called with ${1}"
+
+# dotdrop path can be pass as argument
+ddpath="${cur}/../"
+[ "${1}" != "" ] && ddpath="${1}"
+[ ! -d ${ddpath} ] && echo "ddpath \"${ddpath}\" is not a directory" && exit 1
+
+export PYTHONPATH="${ddpath}:${PYTHONPATH}"
+bin="python3 -m dotdrop.dotdrop"
+
+echo "dotdrop path: ${ddpath}"
+echo "pythonpath: ${PYTHONPATH}"
+
+# get the helpers
+source ${cur}/helpers
+
+echo -e "$(tput setaf 6)==> RUNNING $(basename $BASH_SOURCE) <==$(tput sgr0)"
+
+################################################################
+# this is the test
+################################################################
+
+# dotdrop directory
+basedir=`mktemp -d --suffix='-dotdrop-tests' || mktemp -d`
+echo "[+] dotdrop dir: ${basedir}"
+echo "[+] dotpath dir: ${basedir}/dotfiles"
+
+# the dotfile to be imported
+tmpd=`mktemp -d --suffix='-dotdrop-tests' || mktemp -d`
+
+# some files
+echo "original" > ${tmpd}/singlefile
+
+# create the config file
+cfg="${basedir}/config.yaml"
+cat > ${cfg} << _EOF
+config:
+  backup: true
+  create: true
+  dotpath: dotfiles
+dotfiles:
+profiles:
+_EOF
+
+# import
+echo "[+] import"
+cd ${ddpath} | ${bin} import -c ${cfg} ${tmpd}/singlefile
+
+# modify the file
+echo "modified" > ${tmpd}/singlefile
+
+# normal diff
+echo "[+] comparing with normal diff"
+set +e
+cd ${ddpath} | ${bin} compare -c ${cfg} 2>&1 | grep -v '=>' > ${tmpd}/normal
+diff -r ${tmpd}/singlefile ${basedir}/dotfiles/${tmpd}/singlefile > ${tmpd}/real
+set -e
+
+# verify
+#cat ${tmpd}/normal
+#cat ${tmpd}/real
+diff ${tmpd}/normal ${tmpd}/real || exit 1
+
+# adding unified diff
+cfg2="${basedir}/config2.yaml"
+sed '/dotpath: dotfiles/a \ \ diff_command: "diff -u {0} {1}"' ${cfg} > ${cfg2}
+#cat ${cfg2}
+
+# unified diff
+echo "[+] comparing with unified diff"
+set +e
+cd ${ddpath} | ${bin} compare -c ${cfg2} 2>&1 | grep -v '=>' | grep -v '^+++\|^---' > ${tmpd}/unified
+diff -u ${tmpd}/singlefile ${basedir}/dotfiles/${tmpd}/singlefile | grep -v '^+++\|^---' > ${tmpd}/real
+set -e
+
+# verify
+#cat ${tmpd}/unified
+#cat ${tmpd}/real
+diff ${tmpd}/unified ${tmpd}/real || exit 1
+
+# adding fake diff
+cfg3="${basedir}/config3.yaml"
+sed '/dotpath: dotfiles/a \ \ diff_command: "echo fakediff"' ${cfg} > ${cfg3}
+cat ${cfg3}
+
+# fake diff
+echo "[+] comparing with fake diff"
+set +e
+cd ${ddpath} | ${bin} compare -c ${cfg3} 2>&1 | grep -v '=>' > ${tmpd}/fake
+set -e
+
+# verify
+cat ${tmpd}/fake
+grep fakediff ${tmpd}/fake || exit 1
+
+## CLEANING
+rm -rf ${basedir} ${tmpd}
+
+echo "OK"
+exit 0
diff --git a/tests/helpers.py b/tests/helpers.py
index 997a487..cc6b958 100644
--- a/tests/helpers.py
+++ b/tests/helpers.py
@@ -157,7 +157,6 @@ def load_options(confpath, profile):
     o.import_link = LinkTypes.NOLINK
     o.install_showdiff = True
     o.debug = True
-    o.compare_dopts = ''
     o.variables = {}
     return o