diff --git a/m-algo.h b/m-algo.h
index cd34648d..83e60cea 100644
--- a/m-algo.h
+++ b/m-algo.h
@@ -218,6 +218,25 @@
     *max_p = max;                                                       \
   }                                                                     \
                                                                         \
+  static inline bool M_C(name, _sort_p)(container_t l)                  \
+  {                                                                     \
+    it_t it1;                                                           \
+    it_t it2;                                                           \
+    M_GET_IT_FIRST cont_oplist (it1, l);                                \
+    M_GET_IT_SET cont_oplist (it2, it1);                                \
+    M_GET_IT_NEXT cont_oplist (it2);                                    \
+    while (!M_GET_IT_END_P cont_oplist (it2)) {                         \
+      const type_t *ref1 = M_GET_IT_CREF cont_oplist (it1);             \
+      const type_t *ref2 = M_GET_IT_CREF cont_oplist (it2);             \
+      if (M_GET_CMP type_oplist (*ref1, *ref2) > 0) {                   \
+        return false;                                                   \
+      }                                                                 \
+      M_GET_IT_SET cont_oplist (it1, it2);                              \
+      M_GET_IT_NEXT cont_oplist (it2);                                  \
+    }                                                                   \
+    return true;                                                        \
+  }                                                                     \
+                                                                        \
   /* Sort can be generated from 3 algorithms: */                        \
   /*  - a specialized version defined by the container */               \
   /*  - an insertion sort (need 'previous' method) */                   \
diff --git a/tests/test-malgo.c b/tests/test-malgo.c
index f51dc518..1c03e50e 100644
--- a/tests/test-malgo.c
+++ b/tests/test-malgo.c
@@ -54,8 +54,9 @@ static void test_list(void)
   for(int i = -100; i < 100; i+=2)
     list_int_push_back (l, i);
 
+  assert (!algo_list_sort_p(l));
   algo_list_sort(l);
-  // TODO: assert (algo_list_sort_p(l));
+  assert (algo_list_sort_p(l));
   
   list_int_clear(l);