diff --git a/c_src/stats.h b/c_src/stats.h
index 4f3009f..4fa574b 100644
--- a/c_src/stats.h
+++ b/c_src/stats.h
@@ -128,9 +128,13 @@ static unsigned int __log2_64(uint64_t x) {
      {                                                                  \
          uint8_t logs[64];                                              \
          uint8_t i, j, max_log = 0;                                     \
-         double m = (s->mean + name ## _stat_mean(s) / 2.0);            \
+         double m = 0.0;						\
                                                                         \
-         fprintf(stderr, "%s:async_nif request latency histogram:\n", mod); \
+	 if (s->n < nsamples)						\
+	     return;							\
+									\
+         fprintf(stderr, "\n%s:async_nif request latency histogram:\n", mod); \
+	 m = (s->mean + name ## _stat_mean(s) / 2.0);			\
          for (i = 0; i < 64; i++) {                                     \
              logs[i] = LOG2(s->histogram[i]);                           \
              if (logs[i] > max_log)                                     \
@@ -145,7 +149,7 @@ static unsigned int __log2_64(uint64_t x) {
                  fprintf(stderr, logs[j] >= i ?  "•" : " ");            \
              fprintf(stderr, "\n");                                     \
          }                                                              \
-         if (max_log == 0) {                                            \
+         if (max_log == 100) {                                          \
              fprintf(stderr, "[empty]\n");                              \
          } else {                                                       \
              fprintf(stderr, "     ns        μs        ms        s         ks\n"); \
diff --git a/rebar b/rebar
deleted file mode 100755
index 44053a5..0000000
Binary files a/rebar and /dev/null differ
diff --git a/rebar.config b/rebar.config
index 559c316..8d2088d 100644
--- a/rebar.config
+++ b/rebar.config
@@ -7,7 +7,6 @@
 
 {erl_opts, [%{d,'DEBUG',true},
             debug_info,
-            fail_on_warning,
             warn_unused_vars,
             warn_export_all,
             warn_shadow_vars,
@@ -21,7 +20,8 @@
             warn_exported_vars,
             warn_untyped_record
             %warn_missing_spec,
-            %strict_validation
+            %strict_validation,
+            %fail_on_warning
             ]}.
 
 {xref_checks, [undefined_function_calls, deprecated_function_calls]}.
diff --git a/src/lmdb.erl b/src/lmdb.erl
index 160d491..afebbcb 100644
--- a/src/lmdb.erl
+++ b/src/lmdb.erl
@@ -32,7 +32,7 @@
 %% EXPORTS
 %%====================================================================
 -export([
-         open/1,
+         %open/1,
          open/2,
          open/3,
 
@@ -53,7 +53,7 @@
 %% config for testing
 -ifdef(TEST).
 -ifdef(EQC).
-include_lib("eqc/include/eqc.hrl").
+-include_lib("eqc/include/eqc.hrl").
 -define(QC_OUT(P), eqc:on_output(fun(Str, Args) -> io:format(user, Str, Args) end, P)).
 -endif.
 -include_lib("eunit/include/eunit.hrl").
@@ -80,8 +80,8 @@ include_lib("eqc/include/eqc.hrl").
 %% @doc Create a new MDB database
 %% @end
 %%--------------------------------------------------------------------
-open(DirName) ->
-    open(DirName, ?MDB_MAP_SIZE).
+%open(DirName) ->
+%    open(DirName, ?MDB_MAP_SIZE).
 open(DirName, MapSize)
   when is_integer(MapSize)
        andalso MapSize > 0 ->
@@ -171,20 +171,21 @@ not_loaded(Line) ->
 %% ===================================================================
 -ifdef(TEST).
 
--define(TEST_DATA_DIR, "test/basics").
-
-open_test_db(DataDir) ->
+open_test_db() ->
     {ok, CWD} = file:get_cwd(),
-    Path = filename:join([CWD, DataDir]),
-    ?cmd("rm -rf " ++ Path),
-    ?assertMatch(ok, filelib:ensure_dir(filename:join([Path, "x"]))),
-    {ok, Handle} = ?MODULE:open(Path),
+    DataDir = filename:join([CWD, "test", "eunit"]),
+    ?cmd("rm -rf " ++ DataDir),
+    ?assertMatch(ok, filelib:ensure_dir(filename:join([DataDir, "x"]))),
+    {ok, Handle} = ?MODULE:open(DataDir, 2147483648),
+    [?MODULE:upd(Handle, crypto:sha(<<X>>),
+		 crypto:rand_bytes(crypto:rand_uniform(128, 4096))) ||
+	X <- lists:seq(1, 100)],
     Handle.
 
 basics_test_() ->
     {setup,
      fun() ->
-             open_test_db(?TEST_DATA_DIR)
+             open_test_db()
      end,
      fun(Handle) ->
              ok = ?MODULE:close(Handle)
@@ -193,16 +194,16 @@ basics_test_() ->
              {inorder,
               [{"open and close a database",
                 fun() ->
-                        Handle = open_test_db(Handle)
+                        Handle = open_test_db()
                 end},
                {"create, then drop an empty database",
                 fun() ->
-                        Handle = open_test_db(Handle),
+                        Handle = open_test_db(),
                         ?assertMatch(ok, ?MODULE:drop(Handle))
                 end},
                {"create, put an item, get it, then drop the database",
                 fun() ->
-                        Handle = open_test_db(Handle),
+                        Handle = open_test_db(),
                         ?assertMatch(ok, ?MODULE:put(Handle, <<"a">>, <<"apple">>)),
                         ?assertMatch(ok, ?MODULE:put(Handle, <<"b">>, <<"boy">>)),
                         ?assertMatch(ok, ?MODULE:put(Handle, <<"c">>, <<"cat">>)),
@@ -216,4 +217,63 @@ basics_test_() ->
               ]}
      end}.
 
+-ifdef(EQC).
+
+qc(P) ->
+    ?assert(eqc:quickcheck(?QC_OUT(P))).
+
+keys() ->
+    eqc_gen:non_empty(list(eqc_gen:non_empty(binary()))).
+
+values() ->
+    eqc_gen:non_empty(list(binary())).
+
+ops(Keys, Values) ->
+    {oneof([put, delete]), oneof(Keys), oneof(Values)}.
+
+apply_kv_ops([], _Handle, Acc0) ->
+    Acc0;
+apply_kv_ops([{put, K, V} | Rest], Handle, Acc0) ->
+    ok = ?MODULE:put(Handle, K, V),
+    apply_kv_ops(Rest, Handle, orddict:store(K, V, Acc0));
+apply_kv_ops([{del, K, _} | Rest], Handle, Acc0) ->
+    ok = case ?MODULE:del(Handle, K) of
+             ok ->
+                 ok;
+             not_found ->
+                 ok;
+             Else ->
+                 Else
+         end,
+    apply_kv_ops(Rest, Handle, orddict:store(K, deleted, Acc0)).
+
+prop_put_delete() ->
+    ?LET({Keys, Values}, {keys(), values()},
+         ?FORALL(Ops, eqc_gen:non_empty(list(ops(Keys, Values))),
+                 begin
+                     {ok, CWD} = file:get_cwd(),
+		     DataDir = filename:join([CWD, "test", "eqc"]),
+                     ?cmd("rm -rf " ++ DataDir),
+                     ok = filelib:ensure_dir(filename:join([DataDir, "x"])),
+                     {ok, Handle} = ?MODULE:open(DataDir, 2147483648),
+                     try
+                         Model = apply_kv_ops(Ops, Handle, []),
+
+                         %% Validate that all deleted values return not_found
+                         F = fun({K, deleted}) ->
+                                     ?assertEqual(not_found, ?MODULE:get(Handle, K));
+                                ({K, V}) ->
+                                     ?assertEqual({ok, V}, ?MODULE:get(Handle, K))
+                             end,
+                         lists:map(F, Model),
+                         true
+                     after
+                         ?MODULE:close(Handle)
+                     end
+                 end)).
+
+prop_put_delete_test_() ->
+    {timeout, 3*60, fun() -> qc(prop_put_delete()) end}.
+
+-endif.
 -endif.