diff --git a/spacy/util.py b/spacy/util.py
index afed4142e..457534302 100644
--- a/spacy/util.py
+++ b/spacy/util.py
@@ -94,8 +94,13 @@ def read_regex(path):
 
 
 def compile_prefix_regex(entries):
-    expression = '|'.join(['^' + re.escape(piece) for piece in entries if piece.strip()])
-    return re.compile(expression)
+    if '(' in entries:
+        # Handle deprecated data
+        expression = '|'.join(['^' + re.escape(piece) for piece in entries if piece.strip()])
+        return re.compile(expression)
+    else:
+        expression = '|'.join(['^' + piece for piece in entries if piece.strip()])
+        return re.compile(expression)
 
 
 def compile_suffix_regex(entries):