diff --git a/tools/sequences/kernel b/tools/sequences/kernel
index f0773627d1..f1db7ad4b8 100644
--- a/tools/sequences/kernel
+++ b/tools/sequences/kernel
@@ -12,7 +12,7 @@ tools/mlyacc/mlyacclib
 [poly]src/portableML/poly
 src/portableML
 src/portableML/monads
-src/portableML/json
+[poly]src/portableML/json
 [poly]src/portableML/poly/concurrent
 [mosml]src/portableML/mosml/concurrent
 !src/portableML/testsrc