diff --git a/new/bison.jam b/new/bison.jam
index c43811009..d24c3a70d 100644
--- a/new/bison.jam
+++ b/new/bison.jam
@@ -4,6 +4,8 @@
 #  warranty, and with no claim as to its suitability for any purpose.
 
 import generators ;
+import feature ;
+import type ;
 
 feature.feature bison.prefix : : free ;
 type.register Y : y ;
diff --git a/v2/bison.jam b/v2/bison.jam
index c43811009..d24c3a70d 100644
--- a/v2/bison.jam
+++ b/v2/bison.jam
@@ -4,6 +4,8 @@
 #  warranty, and with no claim as to its suitability for any purpose.
 
 import generators ;
+import feature ;
+import type ;
 
 feature.feature bison.prefix : : free ;
 type.register Y : y ;