diff --git a/larigira/audiogen_randomdir.py b/larigira/audiogen_randomdir.py
index 2453210..fdd99f7 100644
--- a/larigira/audiogen_randomdir.py
+++ b/larigira/audiogen_randomdir.py
@@ -3,11 +3,25 @@ import logging
 import shutil
 import random
 from tempfile import mkstemp
+from pathlib import Path
 
-from larigira.fsutils import scan_dir, shortname
+from larigira.fsutils import scan_dir_audio, shortname, is_audio
 log = logging.getLogger(__name__)
 
 
+def candidates(paths):
+    c = set()
+    for path in paths:
+        if not path.exists():
+            log.warning("Can't find requested path: %s", path)
+            continue
+        if path.is_file() and is_audio(str(path)):
+            c.add(str(path))
+        elif path.is_dir():
+            c.update(scan_dir_audio(str(path)))
+    return c
+
+
 def generate(spec):
     '''
     resolves audiospec-randomdir
@@ -21,18 +35,12 @@ def generate(spec):
         if attr not in spec:
             raise ValueError("Malformed audiospec: missing '%s'" % attr)
 
-    found_files = set()
-    for path in spec['paths']:
-        if not os.path.exists(path):
-            log.warning("Can't find requested path: %s", path)
-            continue
-        if os.path.isfile(path):
-            found_files.add(path)
-        elif os.path.isdir(path):
-            found_files.update(scan_dir(path))
+    found_files = candidates([Path(p) for p in spec['paths']])
 
     picked = random.sample(found_files, int(spec['howmany']))
 
+    # TODO: use specnick
+    nick = spec.get('nick', spec.eid)
     for path in picked:
         tmp = mkstemp(suffix=os.path.splitext(path)[-1],
                       prefix='randomdir-%s-' % shortname(path))
diff --git a/larigira/fsutils.py b/larigira/fsutils.py
index 6501e21..0cdbf41 100644
--- a/larigira/fsutils.py
+++ b/larigira/fsutils.py
@@ -1,5 +1,6 @@
 import os
 import fnmatch
+import mimetypes
 
 
 def scan_dir(dirname, extension=None):
@@ -17,10 +18,15 @@ def multi_fnmatch(fname, extensions):
     return False
 
 
+def is_audio(fname):
+    mimetype = mimetypes.guess_type(fname)[0]
+    return mimetype.split('/')[0] == 'audio'
+
+
 def scan_dir_audio(dirname, extensions=('mp3', 'oga', 'wav', 'ogg')):
     for root, dirnames, filenames in os.walk(dirname):
         for fname in filenames:
-            if multi_fnmatch(fname, extensions):
+            if is_audio(fname):
                 yield os.path.join(root, fname)
 
 
diff --git a/larigira/tests/test_audiogen_randomdir.py b/larigira/tests/test_audiogen_randomdir.py
index 36c92fe..95944ae 100644
--- a/larigira/tests/test_audiogen_randomdir.py
+++ b/larigira/tests/test_audiogen_randomdir.py
@@ -1,18 +1,45 @@
-from gevent import monkey
-monkey.patch_all(subprocess=True)
+from pathlib import Path
 
-import pytest
-
-from larigira.audiogen_randomdir import generate
+from larigira.audiogen_randomdir import candidates
 
 
-@pytest.fixture
-def simplerandom():
-    return {
-        'paths': '/tmp/do/not/exist',
-    }
+def P(pypathlocal):
+    return Path(str(pypathlocal))
 
 
-def test_accepted_syntax(simplerandom):
-    '''Check the minimal needed configuration for randomdir'''
-    generate(simplerandom)
+def test_txt_files_are_excluded(tmpdir):
+    p = tmpdir.join("foo.txt")
+    p.write('')
+    assert len(candidates([P(p)])) == 0
+    assert len(candidates([P(tmpdir)])) == 0
+
+
+def test_nested_txt_files_are_excluded(tmpdir):
+    p = tmpdir.mkdir('one').mkdir('two').join("foo.txt")
+    p.write('')
+    assert len(candidates([P(p)])) == 0
+    assert len(candidates([P(tmpdir)])) == 0
+
+
+def test_mp3_files_are_considered(tmpdir):
+    p = tmpdir.join("foo.mp3")
+    p.write('')
+    assert len(candidates([P(p)])) == 1
+    assert len(candidates([P(tmpdir)])) == 1
+
+
+def test_nested_mp3_files_are_considered(tmpdir):
+    p = tmpdir.mkdir('one').mkdir('two').join("foo.mp3")
+    p.write('')
+    assert len(candidates([P(p)])) == 1
+    assert len(candidates([P(tmpdir)])) == 1
+
+
+def test_same_name(tmpdir):
+    '''file with same name on different dir should not be confused'''
+    p = tmpdir.mkdir('one').mkdir('two').join("foo.mp3")
+    p.write('')
+    p = tmpdir.join("foo.mp3")
+    p.write('')
+
+    assert len(candidates([P(tmpdir)])) == 2