diff --git a/ltablib.c b/ltablib.c
index 4db3768a..baa7111e 100644
--- a/ltablib.c
+++ b/ltablib.c
@@ -298,14 +298,14 @@ static IdxT partition (lua_State *L, IdxT lo, IdxT up) {
   for (;;) {
     /* next loop: repeat ++i while a[i] < P */
     while ((void)geti(L, 1, ++i), sort_comp(L, -1, -2)) {
-      if (l_unlikely(i == up - 1))  /* a[i] < P  but a[up - 1] == P  ?? */
+      if (l_unlikely(i == up - 1))  /* a[up - 1] < P == a[up - 1] */
         luaL_error(L, "invalid order function for sorting");
       lua_pop(L, 1);  /* remove a[i] */
     }
-    /* after the loop, a[i] >= P and a[lo .. i - 1] < P */
+    /* after the loop, a[i] >= P and a[lo .. i - 1] < P  (a) */
     /* next loop: repeat --j while P < a[j] */
     while ((void)geti(L, 1, --j), sort_comp(L, -3, -1)) {
-      if (l_unlikely(j < i))  /* j < i  but  a[j] > P ?? */
+      if (l_unlikely(j < i))  /* j <= i - 1 and a[j] > P, contradicts (a) */
         luaL_error(L, "invalid order function for sorting");
       lua_pop(L, 1);  /* remove a[j] */
     }