diff --git a/spacy/util.py b/spacy/util.py
index afed4142e..592f8e9dd 100644
--- a/spacy/util.py
+++ b/spacy/util.py
@@ -108,6 +108,12 @@ def compile_infix_regex(entries):
     return re.compile(expression)
 
 
+def update_exc(exc, additions):
+    overlap = set(exc.keys()).intersection(set(additions))
+    assert not overlap, overlap
+    exc.update(additions)
+
+
 def normalize_slice(length, start, stop, step=None):
     if not (step is None or step == 1):
         raise ValueError("Stepped slices not supported in Span objects."