diff --git a/vc_zoom/README.md b/vc_zoom/README.md
index f7707e0..29910c8 100644
--- a/vc_zoom/README.md
+++ b/vc_zoom/README.md
@@ -11,6 +11,10 @@
 
 ## Changelog
 
+### 3.1.3
+
+- Fix error with user identifiers (in "authenticators" lookup mode) containing a forward slash
+
 ### 3.1.2
 
 - Do not include Zoom link in event descriptions returned by the HTTP API (iCalendar files for
diff --git a/vc_zoom/indico_vc_zoom/util.py b/vc_zoom/indico_vc_zoom/util.py
index 550560e..14ca253 100644
--- a/vc_zoom/indico_vc_zoom/util.py
+++ b/vc_zoom/indico_vc_zoom/util.py
@@ -60,7 +60,8 @@ def _iter_user_identifiers(user):
     done = set()
     for provider in ZoomPlugin.settings.get('authenticators'):
         for __, identifier in user.iter_identifiers(check_providers=True, providers={provider}):
-            if identifier in done:
+            # skip garbage that breaks API calls; a valid identifier will never contain a slash..
+            if identifier in done or '/' in identifier:
                 continue
             done.add(identifier)
             yield identifier
diff --git a/vc_zoom/setup.cfg b/vc_zoom/setup.cfg
index cb3720f..cbd3ef2 100644
--- a/vc_zoom/setup.cfg
+++ b/vc_zoom/setup.cfg
@@ -1,6 +1,6 @@
 [metadata]
 name = indico-plugin-vc-zoom
-version = 3.1.2
+version = 3.1.3
 description = Zoom video-conferencing plugin for Indico
 long_description = file: README.md
 long_description_content_type = text/markdown; charset=UTF-8; variant=GFM