diff --git a/regression/cbmc/union/union_member.desc b/regression/cbmc/union/union_member.desc
index a2b273bfe0f..b2831085263 100644
--- a/regression/cbmc/union/union_member.desc
+++ b/regression/cbmc/union/union_member.desc
@@ -1,4 +1,4 @@
-CORE broken-smt-backend
+CORE broken-z3-smt-backend
 union_member.c
 
 ^EXIT=10$
diff --git a/regression/cbmc/union/union_update.desc b/regression/cbmc/union/union_update.desc
index 8f8f7b852b0..623c206a41f 100644
--- a/regression/cbmc/union/union_update.desc
+++ b/regression/cbmc/union/union_update.desc
@@ -1,4 +1,4 @@
-CORE broken-smt-backend
+CORE broken-z3-smt-backend
 union_update.c
 
 ^EXIT=10$