diff --git a/libcxx/include/__random/seed_seq.h b/libcxx/include/__random/seed_seq.h
--- a/libcxx/include/__random/seed_seq.h
+++ b/libcxx/include/__random/seed_seq.h
@@ -109,7 +109,8 @@
             __first[__q] += __r;
             __first[0] = __r;
         }
-        // initialize {(__k + x) % __n} indexing terms
+        // Initialize indexing terms used with if statements as an optimization to
+        // avoid calculating modulo n on every loop iteration for each term.
         size_t __kmodn = 0;          // __k % __n
         size_t __k1modn = __n - 1;   // (__k - 1) % __n
         size_t __kpmodn = __p % __n; // (__k + __p) % __n