diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 1dcd532ad..93834bec6 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -1,5 +1,5 @@
 %glr-parser
-%pure-parser
+%define api.pure
 %locations
 %define parse.error verbose
 %defines