diff --git a/bob/devtools/log.py b/bob/devtools/log.py
index 8ccad76117833b12e0e5f9f98a6157b67d2076dc..226ccf0ad8c6c620d2260903bd9080f8d4b0a276 100644
--- a/bob/devtools/log.py
+++ b/bob/devtools/log.py
@@ -229,3 +229,18 @@ def verbosity_option(**kwargs):
             "(e.g. '-vvv' for debug).",
             callback=callback, **kwargs)(f)
     return custom_verbosity_option
+
+
+def open_files():
+    '''Returns the number of open file descriptors for current process
+
+    .. warning: will only work on UNIX-like os-es.
+
+    '''
+
+    import os
+    import subprocess
+
+    pid = os.getpid()
+    procs = subprocess.check_output(['lsof', '-w', '-p', str(pid)])
+    return [k.split()[-1].decode('ascii') for k in procs.split(b'\n') if k][1:]
diff --git a/bob/devtools/scripts/ci.py b/bob/devtools/scripts/ci.py
index 29327f69576af396622917f592123b5beac2736c..0f28a032beed3cd3352585eeb887ea5281d8be50 100644
--- a/bob/devtools/scripts/ci.py
+++ b/bob/devtools/scripts/ci.py
@@ -16,7 +16,7 @@ from ..constants import SERVER, CONDA_BUILD_CONFIG, CONDA_RECIPE_APPEND, \
     WEBDAV_PATHS, BASE_CONDARC
 from ..deploy import deploy_conda_package, deploy_documentation
 
-from ..log import verbosity_option, get_logger, echo_normal
+from ..log import verbosity_option, get_logger, echo_normal, open_files
 logger = get_logger(__name__)
 
 
@@ -481,7 +481,6 @@ def nightlies(ctx, order, dry_run):
   token = os.environ['CI_JOB_TOKEN']
 
   import git
-  import psutil
   from .build import build
   from urllib.request import urlopen
 
@@ -510,8 +509,9 @@ def nightlies(ctx, order, dry_run):
     private = urlopen('https://gitlab.idiap.ch/%s' % package).getcode() != 200
     stable = 'STABLE' in os.environ
 
+    current_open_files = open_files()
     logger.warn('Number of open files before build: %d',
-      len(psutil.Process().open_files()))
+      len(current_open_files))
 
     ctx.invoke(build,
         recipe_dir=[os.path.join(clone_to, 'conda')],
@@ -528,8 +528,10 @@ def nightlies(ctx, order, dry_run):
         ci=True,
         )
 
-    logger.warn('Number of open files after build: %d',
-      len(psutil.Process().open_files()))
+    after_open_files = open_files()
+    logger.warn('Number of open files after build: %d', len(after_open_files))
+    logger.warn('New files opened: %s',
+        ', '.join(list(set(after_open_files) - set(current_open_files))))
 
     is_master = os.environ['CI_COMMIT_REF_NAME'] == 'master'