diff --git a/bob/devtools/scripts/ci.py b/bob/devtools/scripts/ci.py
index e00f127d8980ea546fcd3eb5e119a3e3f161292f..9c9ee3d4e87d253316bce57471acb62819864eaf 100644
--- a/bob/devtools/scripts/ci.py
+++ b/bob/devtools/scripts/ci.py
@@ -481,6 +481,7 @@ 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
 
@@ -509,6 +510,9 @@ def nightlies(ctx, order, dry_run):
     private = urlopen('https://gitlab.idiap.ch/%s' % package).getcode() != 200
     stable = 'STABLE' in os.environ
 
+    logger.warn('Number of open files before build: %d',
+      len(psutil.Process().open_files())
+
     ctx.invoke(build,
         recipe_dir=[os.path.join(clone_to, 'conda')],
         python=os.environ['PYTHON_VERSION'],  #python version
@@ -524,6 +528,9 @@ def nightlies(ctx, order, dry_run):
         ci=True,
         )
 
+    logger.warn('Number of open files after build: %d',
+      len(psutil.Process().open_files())
+
     is_master = os.environ['CI_COMMIT_REF_NAME'] == 'master'
 
     # re-deploys a new conda package if it was rebuilt and it is the master