diff --git a/drama/src/rev-mc.c b/drama/src/rev-mc.c
index da21620..cdc1873 100644
--- a/drama/src/rev-mc.c
+++ b/drama/src/rev-mc.c
@@ -370,10 +370,10 @@ find_row_mask(std::vector<set_t> &sets,
                     }
                 }
 
-                for (int i = 0; i < step && cur_mask < last_mask; ++i) {
-                    if (!found.load(std::memory_order_relaxed) && resolve(cur_mask)) {
-                        std::lock_guard<std::mutex> _(lock);
+                for (int i = 0; i < step && cur_mask < last_mask && !found.load(std::memory_order_relaxed); ++i) {
+                    if (resolve(cur_mask)) {
                         if (!found.exchange(true)) {
+                            std::lock_guard<std::mutex> _(lock);
                             row_mask = cur_mask;
                             break;
                         }