diff --git a/lib/Semantics/check-omp-structure.cpp b/lib/Semantics/check-omp-structure.cpp
index 3b58f97..2c1b291 100644
--- a/lib/Semantics/check-omp-structure.cpp
+++ b/lib/Semantics/check-omp-structure.cpp
@@ -1391,6 +1391,7 @@
 CHECK_SIMPLE_CLAUSE(Novariants, OMPC_novariants)
 CHECK_SIMPLE_CLAUSE(Nocontext, OMPC_nocontext)
 CHECK_SIMPLE_CLAUSE(Filter, OMPC_filter)
+CHECK_SIMPLE_CLAUSE(When, OMPC_when)
 
 CHECK_REQ_SCALAR_INT_CLAUSE(Grainsize, OMPC_grainsize)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumTasks, OMPC_num_tasks)