diff --git a/participation/forms.py b/participation/forms.py
index 0ce2096..c518001 100644
--- a/participation/forms.py
+++ b/participation/forms.py
@@ -262,7 +262,15 @@ class UploadNotesForm(forms.Form):
                     except UnicodeDecodeError:
                         # This is not UTF-8, grrrr
                         content = data.decode('latin1')
-                    csvfile = csv.reader(StringIO(content))
+                    for delimiter in [',', ';', '\t', '|']:
+                        if content.split('\n')[0].count(delimiter) > 1:
+                            break
+                    else:
+                        self.add_error('file',
+                                       _("Unable to detect the CSV delimiter. Please use a comma-separated file."))
+                        return cleaned_data
+
+                    csvfile = csv.reader(StringIO(content), delimiter=delimiter)
                     self.process(csvfile, cleaned_data)
                 except UnicodeDecodeError:
                     self.add_error('file', _("This file contains non-UTF-8 and non-ISO-8859-1 content. "