diff --git a/README.md b/README.md
index 780ec25..4803b18 100644
--- a/README.md
+++ b/README.md
@@ -620,10 +620,15 @@ probably confuse the process.
     open(Drv, Path, Flags, Mode) -> {ok, integer()} | {error, posix()}
     open(Drv, Pids, Path, Flags, Mode) -> {ok, integer()} | {error, posix()}
 
-        Types   Flags = Mode = integer()
+        Types   Flags = integer() | [atom() | integer()]
+                Mode = integer()
 
         open(2) : returns a file descriptor associated with a file
 
+        Lists of values are OR'ed:
+
+            alcove:open(Drv, "/tmp/test", [o_wronly,o_creat], 8#644)
+
     pid(Drv) -> [Pid]
     pid(Drv, Pids) -> [Pid]
 
diff --git a/bin/alcove.escript b/bin/alcove.escript
index 487bebb..5fddacd 100755
--- a/bin/alcove.escript
+++ b/bin/alcove.escript
@@ -482,8 +482,8 @@ specs() ->
 -spec mount_define(alcove_drv:ref(),atom()) -> 'unknown' | non_neg_integer().
 -spec mount_define(alcove_drv:ref(),fork_path(),atom()) -> 'unknown' | non_neg_integer().
 
--spec open(alcove_drv:ref(),iodata(),integer(),integer()) -> {'ok',fd()} | {'error', file:posix()}.
--spec open(alcove_drv:ref(),fork_path(),iodata(),integer(),integer()) -> {'ok',fd()} | {'error', file:posix()}.
+-spec open(alcove_drv:ref(),iodata(),integer() | [define()],integer()) -> {'ok',fd()} | {'error', file:posix()}.
+-spec open(alcove_drv:ref(),fork_path(),iodata(),integer() | [define()],integer()) -> {'ok',fd()} | {'error', file:posix()}.
 
 -spec pid(alcove_drv:ref()) -> [#alcove_pid{}].
 -spec pid(alcove_drv:ref(),fork_path()) -> [#alcove_pid{}].
diff --git a/c_src/alcove.h b/c_src/alcove.h
index 6da2749..e6ee234 100644
--- a/c_src/alcove.h
+++ b/c_src/alcove.h
@@ -176,6 +176,8 @@ int alcove_decode_list_header(const char *, size_t, int *, int *);
 int alcove_decode_tuple_header(const char *, size_t, int *, int *);
 int alcove_decode_iolist(const char *, size_t, int *, char *, size_t *);
 int alcove_decode_define(const char *, size_t, int *, int *, alcove_define_t *);
+int alcove_decode_define_list(const char *, size_t, int *, int *,
+        alcove_define_t *);
 
 int alcove_encode_version(char *, size_t, int *);
 int alcove_encode_list_header(char *, size_t, int *, int);
diff --git a/c_src/alcove_file.c b/c_src/alcove_file.c
index d2c4228..dac55ce 100644
--- a/c_src/alcove_file.c
+++ b/c_src/alcove_file.c
@@ -48,7 +48,8 @@ alcove_open(alcove_state_t *ap, const char *arg, size_t len,
         return -1;
 
     /* flags */
-    if (alcove_decode_int(arg, len, &index, &flags) < 0)
+    if (alcove_decode_define_list(arg, len, &index, &flags,
+                alcove_file_constants) < 0)
         return -1;
 
     /* mode */
diff --git a/c_src/alcove_term.c b/c_src/alcove_term.c
index 556bc1f..a8714e1 100644
--- a/c_src/alcove_term.c
+++ b/c_src/alcove_term.c
@@ -313,6 +313,70 @@ alcove_decode_define(const char *buf, size_t len, int *index, int *val,
             return -1;
     }
 
+    return 0;
+}
+
+    int
+alcove_decode_define_list(const char *buf, size_t len, int *index, int *val,
+        alcove_define_t *constants)
+{
+    int type = 0;
+    int arity = 0;
+
+    if (alcove_get_type(buf, len, index, &type, &arity) < 0)
+        return -1;
+
+    switch (type) {
+        case ERL_SMALL_INTEGER_EXT:
+        case ERL_INTEGER_EXT:
+            if (alcove_decode_int(buf, len, index, val) < 0)
+                return -1;
+            break;
+
+        case ERL_STRING_EXT: {
+            char tmp[MAXMSGLEN] = {0};
+            char *p = tmp;
+
+            if (arity >= sizeof(tmp))
+                return -1;
+
+            if (ei_decode_string(buf, index, tmp) < 0)
+                return -1;
+
+            for ( ; *p; p++)
+                *val |= *p;
+
+            }
+            break;
+
+        case ERL_LIST_EXT: {
+            int i = 0;
+            int length = 0;
+            int constant = 0;
+
+            if (ei_decode_list_header(buf, index, &length) < 0)
+                return -1;
+
+            for (i = 0; i < length; i++) {
+                if (alcove_decode_define(buf, len, index, &constant,
+                            constants) < 0)
+                    return -1;
+
+                *val |= constant;
+            }
+
+            /* [] */
+            if (alcove_decode_list_header(buf, len, index, &length) < 0
+                    || length != 0)
+                return -1;
+
+            }
+            break;
+
+        default:
+            return -1;
+    }
+
     return 0;
 }
 
diff --git a/test/alcove_tests.erl b/test/alcove_tests.erl
index a0e7028..6908c63 100644
--- a/test/alcove_tests.erl
+++ b/test/alcove_tests.erl
@@ -68,7 +68,8 @@ run(State) ->
         stdout(State),
         stderr(State),
         execve(State),
-        stream(State)
+        stream(State),
+        open(State)
     ].
 
 start() ->
@@ -594,6 +595,21 @@ stream(#state{pid = Drv}) ->
     Reply = stream_count(Drv, Chain, Count*2),
     ?_assertEqual(ok, Reply).
 
+open(#state{pid = Drv}) ->
+    O_RDONLY = alcove:define(Drv, o_rdonly),
+
+    File = "/nonexistent",
+
+    Reply0 = alcove:open(Drv, File, 0, 0),
+    Reply1 = alcove:open(Drv, File, [0,0,0,0], 0),
+    Reply2 = alcove:open(Drv, File, [o_rdonly, o_rdonly, o_rdonly], 0),
+
+    [
+        ?_assertEqual({error,enoent}, Reply0),
+        ?_assertEqual({error,enoent}, Reply1),
+        ?_assertEqual({error,enoent}, Reply2)
+    ].
+
 %%
 %% Utility functions
 %%