diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index cdc78aa3d4..c71dce4b1e 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -1580,6 +1580,7 @@ uint32_t HELPER(csst)(CPUS390XState *env, uint32_t r3, uint64_t a1, uint64_t a2)
                 cpu_stq_data_ra(env, a2 + 0, svh, ra);
                 cpu_stq_data_ra(env, a2 + 8, svl, ra);
             }
+            break;
         default:
             g_assert_not_reached();
         }