diff --git a/src/geef_blob.erl b/src/geef_blob.erl
index 1bdbf66..707d160 100644
--- a/src/geef_blob.erl
+++ b/src/geef_blob.erl
@@ -6,9 +6,12 @@
 
 -include("geef_records.hrl").
 
+-type blob() :: geef_obj:object(blob).
+-export_type([blob/0]).
+
 -export([lookup/2, size/1, content/1]).
 
--spec lookup(pid(), geef_oid() | iolist()) -> {ok, geef_object()} | {error, term()}.
+-spec lookup(pid(), geef_oid:oid() | iolist()) -> {ok, blob()} | {error, term()}.
 lookup(Repo, Id) ->
     geef_obj:lookup(Repo, Id, blob).
 
diff --git a/src/geef_commit.erl b/src/geef_commit.erl
index e85a22e..7ac0bd6 100644
--- a/src/geef_commit.erl
+++ b/src/geef_commit.erl
@@ -3,11 +3,15 @@
 
 -include("geef_records.hrl").
 
--spec tree_id(geef_object()) -> geef_oid().
+-type commit() :: geef_obj:object(commit).
+-export_type([commit/0]).
+
+-spec tree_id(commit()) -> geef_oid:oid().
 tree_id(#geef_object{type=commit,handle=Handle}) ->
     Oid = geef_nif:commit_tree_id(Handle),
     #geef_oid{oid=Oid}.
 
+-spec tree(commit()) -> {ok, geef_tree:tree()} | {error, term()}.
 tree(#geef_object{type=commit,handle=Handle}) ->
     case geef_nif:commit_tree(Handle) of
 	{ok, Type, Handle} ->
@@ -16,6 +20,6 @@ tree(#geef_object{type=commit,handle=Handle}) ->
 	    Other
     end.
 
--spec lookup(pid(), geef_oid() | iolist()) -> {ok, geef_object()} | {error, term()}.
+-spec lookup(pid(), geef_oid:oid() | iolist()) -> {ok, commit()} | {error, term()}.
 lookup(Repo, Id) ->
     geef_obj:lookup(Repo, Id, commit).
diff --git a/src/geef_index.erl b/src/geef_index.erl
index 4ab93eb..114f485 100644
--- a/src/geef_index.erl
+++ b/src/geef_index.erl
@@ -21,6 +21,9 @@
 -record(state, {handle}).
 -include("geef_records.hrl").
 
+-type entry() :: #geef_index_entry{}.
+-export_type([entry/0]).
+
 %%%===================================================================
 %%% API
 %%%===================================================================
@@ -39,12 +42,12 @@ write(Pid) ->
     gen_server:call(Pid, write).
 
 %% @doc Write out the index's contents to its the repository.
--spec write_tree(pid()) -> {ok, geef_oid()} | {error, term()}.
+-spec write_tree(pid()) -> {ok, geef_oid:oid()} | {error, term()}.
 write_tree(Pid) ->
     gen_server:call(Pid, write_tree).
 
 %% @doc Write out the index's contents to the given repository
--spec write_tree(pid(), pid()) -> {ok, geef_oid()} | {error, term()}.
+-spec write_tree(pid(), pid()) -> {ok, geef_oid:oid()} | {error, term()}.
 write_tree(Pid, Repo) ->
     gen_server:call(Pid, {write_tree, Repo}).
 
@@ -52,7 +55,7 @@ read_tree(Pid, #geef_object{type=tree, handle=TreeHandle}) ->
     gen_server:call(Pid, {read_tree, TreeHandle}).
 
 %% @doc Add an entry to the index
--spec add(pid(), geef_index_entry()) -> ok | {error, term()}.
+-spec add(pid(), entry()) -> ok | {error, term()}.
 add(Pid, Entry) ->
     gen_server:call(Pid, {add, Entry}).
 
diff --git a/src/geef_nif.erl b/src/geef_nif.erl
index ee01c92..c235c95 100644
--- a/src/geef_nif.erl
+++ b/src/geef_nif.erl
@@ -52,11 +52,11 @@ reference_glob(_Repo, _Glob) ->
 reference_lookup(_Repo, _Refname) ->
     nif_error(?LINE).
 
--spec reference_iterator(term(), iolist() | undefined) -> {ok, geef_iterator()} | {error, term()}.
+-spec reference_iterator(term(), iolist() | undefined) -> {ok, geef_ref:iterator()} | {error, term()}.
 reference_iterator(_Repo, _Regexp) ->
     nif_error(?LINE).
 
--spec reference_next(geef_iterator()) -> {ok, term()} | {error, iterover | term()}.
+-spec reference_next(geef_ref:iterator()) -> {ok, term()} | {error, iterover | term()}.
 reference_next(_Handle) ->
     nif_error(?LINE).
 
@@ -69,6 +69,7 @@ reference_resolve(_Handle) ->
 reference_type(_Handle) ->
     nif_error(?LINE).
 
+-spec reference_name(term()) -> {ok, binary()} | {error, term()}.
 reference_name(_Handle) ->
     nif_error(?LINE).
 
diff --git a/src/geef_obj.erl b/src/geef_obj.erl
index b6c186a..f8a4e15 100644
--- a/src/geef_obj.erl
+++ b/src/geef_obj.erl
@@ -6,9 +6,14 @@
 
 -include("geef_records.hrl").
 
+-type object() :: #geef_object{type :: blob | tree | commit | tag}.
+-type object(Type) :: #geef_object{type :: Type}.
+
+-export_type([object/0, object/1]).
+
 -export([lookup/2, lookup/3]).
 
--spec lookup(pid(), geef_oid() | iolist()) -> {ok, geef_object()} | {error, term()}.
+-spec lookup(pid(), geef_oid:oid() | iolist()) -> {ok, object()} | {error, term()}.
 lookup(Repo, Id = #geef_oid{oid=Oid}) ->
     case geef_repo:lookup_object(Repo, Oid) of
 	{ok, Type, Handle} ->
@@ -20,7 +25,7 @@ lookup(Repo, Id) ->
     lookup(Repo, geef_oid:parse(Id)).
 
 %% As lookup/2, but it asserts that the type is correct
--spec lookup(pid(), geef_oid() | iolist(), atom()) -> {ok, geef_object()} | {error, term()}.
+-spec lookup(pid(), geef_oid:oid() | iolist(), atom()) -> {ok, object()} | {error, term()}.
 lookup(Repo, Id, Type) ->
     case lookup(Repo, Id) of
 	{ok, Obj = #geef_object{type=Type}} ->
diff --git a/src/geef_odb.erl b/src/geef_odb.erl
index cde6927..a848c34 100644
--- a/src/geef_odb.erl
+++ b/src/geef_odb.erl
@@ -84,14 +84,14 @@ code_change(_OldVsn, State, _Extra) ->
 -include_lib("eunit/include/eunit.hrl").
 -endif.
 
--spec exists(pid(), geef_oid() | iolist()) -> boolean().
+-spec exists(pid(), geef_oid:oid() | iolist()) -> boolean().
 exists(Pid, #geef_oid{oid=Oid}) ->
     gen_server:call(Pid, {exists, Oid});
 exists(Pid, Sha) ->
     #geef_oid{oid=Oid} = geef_oid:parse(Sha),
     gen_server:call(Pid, {exists, Oid}).
 
--spec write(pid(), iolist(), atom()) -> {ok, geef_oid()} | {error, term()}.
+-spec write(pid(), iolist(), atom()) -> {ok, geef_oid:oid()} | {error, term()}.
 write(Pid, Contents, Type) ->
     gen_server:call(Pid, {write, Contents, Type}).
 
diff --git a/src/geef_oid.erl b/src/geef_oid.erl
index 4b51350..c39042d 100644
--- a/src/geef_oid.erl
+++ b/src/geef_oid.erl
@@ -7,15 +7,18 @@
 
 -include("geef_records.hrl").
 
+-type oid() :: #geef_oid{oid :: binary()}.
+-export_type([oid/0]).
+
 -export([parse/1, hex/1]).
 
 %% @doc Get a hex-encoded string of the hash
--spec hex(geef_oid()) -> binary().
+-spec hex(geef_oid:oid()) -> binary().
 hex(#geef_oid{oid=Oid}) ->
     geef_nif:oid_fmt(Oid).
 
 %% @doc Parse an iolist as a hash
--spec parse(iolist() | binary()) -> geef_oid().
+-spec parse(iolist() | binary()) -> geef_oid:oid().
 parse(Sha) ->
     Oid = geef_nif:oid_parse(Sha),
     #geef_oid{oid=Oid}.
diff --git a/src/geef_pkt.erl b/src/geef_pkt.erl
index 48cdcf8..ebee037 100644
--- a/src/geef_pkt.erl
+++ b/src/geef_pkt.erl
@@ -15,7 +15,7 @@ line(Text) ->
     Prefix = io_lib:format("~4.16.0b", [Len]),
     [Prefix, Text, "\n"].
 
--spec parse(iolist()) -> {{want | have, geef_oid()}, binary()} | {error, ebufs}.
+-spec parse(iolist()) -> {{want | have, geef_oid:oid()}, binary()} | {error, ebufs}.
 parse(In) ->
     case unpack(In) of
 	Err = {error, ebufs} ->
@@ -56,7 +56,7 @@ do_unpack(Len, Rest) when Len - 4 > size(Rest) ->
 do_unpack(Len, Rest) ->
     {Len - 4, Rest}.
 
--spec parse_pkt(binary(), non_neg_integer()) -> {{want | have, geef_oid()}, binary()} | {done, binary()} | {flush, binary()}.
+-spec parse_pkt(binary(), non_neg_integer()) -> {{want | have, geef_oid:oid()}, binary()} | {done, binary()} | {flush, binary()}.
 parse_pkt(In, 0) ->
     {flush, In};
 parse_pkt(In, Len) ->
diff --git a/src/geef_records.hrl b/src/geef_records.hrl
index 4ab09db..7ddd4d4 100644
--- a/src/geef_records.hrl
+++ b/src/geef_records.hrl
@@ -1,26 +1,18 @@
--record(geef_reference, {handle, name :: binary(), type :: oid | symbolic, target :: binary() | geef_oid()}).
+-record(geef_reference, {handle, name :: binary(), type :: oid | symbolic, target :: binary() | geef_oid:oid()}).
 -record(geef_oid, {oid :: binary()}).
--record(geef_object, {type :: atom(), id :: geef_oid(), handle}).
+-record(geef_object, {type :: atom(), id :: geef_oid:oid(), handle}).
 -record(geef_index_entry,
 	{ctime :: non_neg_integer(), mtime :: non_neg_integer(),
 	 dev :: non_neg_integer(), ino :: non_neg_integer(),
 	 mode :: non_neg_integer(), uid :: non_neg_integer(), gid :: non_neg_integer(),
 	 size :: non_neg_integer(),
-	 id :: geef_oid(),
+	 id :: geef_oid:oid(),
 	 flags, flags_extended,
 	 path :: iolist()}).
 
 -record(geef_request, {service :: atom(), path :: binary(), host :: binary()}).
 -record(geef_tree_entry, {mode, type, id, name}).
--record(geef_signature, {name :: iolist(), email :: iolist(), time :: geef_time()}).
+-record(geef_signature, {name :: iolist(), email :: iolist(), time :: geef_sig:time()}).
 -record(geef_iterator, {type :: atom(), repo :: pid(), regexp :: iolist(), handle}).
 
--type geef_reference() :: #geef_reference{name :: binary(), target :: binary() | geef_oid()}.
--type geef_oid() :: #geef_oid{oid :: binary()}.
--type geef_object() :: #geef_object{}.
--type geef_index_entry() :: #geef_index_entry{}.
 -type geef_request() :: #geef_request{}.
--type geef_tree_entry() :: #geef_tree_entry{}.
--type geef_signature() :: #geef_signature{}.
--type geef_time() :: {erlang:timestamp(), non_neg_integer()}.
--type geef_iterator() :: #geef_iterator{}.
diff --git a/src/geef_ref.erl b/src/geef_ref.erl
index 4924093..70fe0d0 100644
--- a/src/geef_ref.erl
+++ b/src/geef_ref.erl
@@ -4,12 +4,16 @@
 
 -include("geef_records.hrl").
 
--spec new(term()) -> geef_reference().
+-type iterator() :: #geef_iterator{type :: ref}.
+-type ref() :: #geef_reference{name :: binary()}.
+-export_type([reference/0, iterator/0]).
+
+-spec new(term()) -> ref().
 new(Handle) ->
     {ok, Name} = geef_nif:reference_name(Handle),
     new(Name, Handle).
 
--spec new(binary(), term()) -> geef_reference().
+-spec new(binary(), term()) -> ref().
 new(Name, Handle) ->
     Type = geef_nif:reference_type(Handle),
     Bin = geef_nif:reference_target(Handle),
@@ -21,7 +25,7 @@ new(Name, Handle) ->
 	     end,
     #geef_reference{handle=Handle, name=Name, type=Type, target=Target}.
 
--spec create(pid(), iolist(), geef_oid() | binary(), boolean()) -> {ok, geef_reference()} | {error, term()}.
+-spec create(pid(), iolist(), geef_oid:oid() | binary(), boolean()) -> {ok, ref()} | {error, term()}.
 create(Repo, Refname, Target, Force) ->
     case geef_repo:create_reference(Repo, Refname, Target, Force) of
         {ok, Ref} ->
@@ -30,7 +34,7 @@ create(Repo, Refname, Target, Force) ->
             Err
     end.
 
--spec lookup(pid(), iolist()) -> {ok, geef_reference()} | {error, term()}.
+-spec lookup(pid(), iolist()) -> {ok, ref()} | {error, term()}.
 lookup(Repo, Refname) ->
     Name = iolist_to_binary(Refname),
     case geef_repo:lookup_reference(Repo, Name) of
@@ -40,7 +44,7 @@ lookup(Repo, Refname) ->
 	    Other
     end.
 
--spec iterator(pid(), iolist() | undefined) -> {ok, geef_iterator()} | {error, term()}.
+-spec iterator(pid(), iolist() | undefined) -> {ok, iterator()} | {error, term()}.
 iterator(Repo, Regexp) ->
     case geef_repo:iterator(Repo, Regexp) of
 	{ok, Handle} ->
@@ -49,10 +53,11 @@ iterator(Repo, Regexp) ->
 	    Other
     end.
 
--spec iterator(pid()) -> {ok, geef_iterator()} | {error, term()}.
+-spec iterator(pid()) -> {ok, iterator()} | {error, term()}.
 iterator(Repo) ->
     iterator(Repo, undefined).
 
+-spec next(iterator()) -> {ok, ref()} | {error, term()}.
 next(#geef_iterator{type=ref, handle=Handle}) ->
     case geef_nif:reference_next(Handle) of
 	{ok, RefHandle} ->
@@ -61,18 +66,18 @@ next(#geef_iterator{type=ref, handle=Handle}) ->
 	    Other
     end.
 
--spec resolve(geef_reference()) -> {ok, geef_reference()} | {error, term()}.
+-spec resolve(ref()) -> {ok, ref()} | {error, term()}.
 resolve(Ref = #geef_reference{type=oid}) ->
     {ok, Ref}; % resolving an oid ref is a no-op, skip going into the NIF
-resolve(#geef_reference{handle=Handle}) ->
+resolve(#geef_reference{type=symbolic, handle=Handle}) ->
     case geef_nif:reference_resolve(Handle) of
 	{ok, Ref} ->
 	    {ok, new(Ref)};
-	Other ->
+	Other = {error, _} ->
 	    Other
     end.
 
--spec dwim(pid(), iolist()) -> {ok, geef_reference()} | {error, term()}.
+-spec dwim(pid(), iolist()) -> {ok, ref()} | {error, term()}.
 dwim(Repo, Name) ->
     case geef_repo:reference_dwim(Repo, Name) of
 	{ok, Handle} ->
@@ -82,7 +87,7 @@ dwim(Repo, Name) ->
     end.
 
 %% @doc Get the shorthand name for a particular reference
--spec shorthand(geef_reference() | binary()) -> binary().
+-spec shorthand(ref() | binary()) -> binary().
 shorthand(<<"refs/heads/", Rest/binary>>) ->
     Rest;
 shorthand(<<"refs/tags/", Rest/binary>>) ->
diff --git a/src/geef_repo.erl b/src/geef_repo.erl
index 9f20b08..623df3b 100644
--- a/src/geef_repo.erl
+++ b/src/geef_repo.erl
@@ -87,7 +87,7 @@ lookup_reference(Pid, Name) ->
     gen_server:call(Pid, {lookup_reference, Name}).
 
 %% @private
--spec iterator(pid(), iolist() | undefined) -> {ok, geef_iterator()} | {error, term()}.
+-spec iterator(pid(), iolist() | undefined) -> {ok, geef_ref:iterator()} | {error, term()}.
 iterator(Pid, Regexp) ->
     gen_server:call(Pid, {iterator, Regexp}).
 
diff --git a/src/geef_revwalk.erl b/src/geef_revwalk.erl
index 4920cb4..6a02cca 100644
--- a/src/geef_revwalk.erl
+++ b/src/geef_revwalk.erl
@@ -28,7 +28,7 @@
 %% @doc Push a commit. This commit and its parents will be included in
 %% the walk as long as they haven't been hidden. At least one commit
 %% must be pushed before starting a walk.
--spec push(pid(), geef_oid() | iolist()) -> ok | {error, binary()}.
+-spec push(pid(), geef_oid:oid() | iolist()) -> ok | {error, binary()}.
 push(Pid, #geef_oid{oid=Oid}) ->
     gen_server:call(Pid, {push, Oid});
 push(Pid, Id) ->
@@ -38,7 +38,7 @@ push(Pid, Id) ->
 
 %% @doc Hide a commit. Hide a commit and its parents. Any Parent of
 %% this commit won't be included in the walk.
--spec hide(pid(), geef_oid() | iolist()) -> ok | {error, binary()}.
+-spec hide(pid(), geef_oid:oid() | iolist()) -> ok | {error, binary()}.
 hide(Pid, #geef_oid{oid=Oid}) ->
     gen_server:call(Pid, {hide, Oid});
 hide(Pid, Id) ->
diff --git a/src/geef_sig.erl b/src/geef_sig.erl
index 972fec0..afb7d70 100644
--- a/src/geef_sig.erl
+++ b/src/geef_sig.erl
@@ -2,9 +2,13 @@
 
 -include("geef_records.hrl").
 
+-type time() :: {erlang:timestamp(), non_neg_integer()}.
+-type signature() :: #geef_signature{}.
+-export_type([time/0, signature/0]).
+
 -export([new/2, new/3]).
 
--spec new(iolist(), iolist()) -> {ok, geef_signature()} | {error, term()}.
+-spec new(iolist(), iolist()) -> {ok, signature()} | {error, term()}.
 new(Name0, Email0) ->
     case geef_nif:signature_new(Name0, Email0) of
         {ok, Name, Email, Time0, Offset} ->
@@ -14,7 +18,7 @@ new(Name0, Email0) ->
             Err
     end.
 
--spec new(iolist(), iolist(), geef_time()) ->  {ok, geef_signature()} | {error, term()}.
+-spec new(iolist(), iolist(), time()) ->  {ok, signature()} | {error, term()}.
 new(Name0, Email0, Time) ->
     case geef_nif:signature_new(Name0, Email0, 0) of
         {ok, Name, Email} ->
diff --git a/src/geef_tag.erl b/src/geef_tag.erl
index 4762c93..460cd26 100644
--- a/src/geef_tag.erl
+++ b/src/geef_tag.erl
@@ -8,11 +8,14 @@
 
 -include("geef_records.hrl").
 
--spec lookup(pid(), geef_oid() | iolist()) -> {ok, geef_object()} | {error, term()}.
+-type tag() :: geef_obj:object(tag).
+-export_type([tag/0]).
+
+-spec lookup(pid(), geef_oid:oid() | iolist()) -> {ok, tag()} | {error, term()}.
 lookup(Repo, Id) ->
     geef_obj:lookup(Repo, Id, tag).
 
--spec peel(geef_object()) -> {ok, geef_object()} | {error, term()}.
+-spec peel(tag()) -> {ok, geef_obj:object()} | {error, term()}.
 peel(#geef_object{type=tag, handle=Handle}) ->
     case geef_nif:tag_peel(Handle) of
         {ok, Type, Oid, PeeledHandle} ->
diff --git a/src/geef_tree.erl b/src/geef_tree.erl
index 2f9dc31..3f55444 100644
--- a/src/geef_tree.erl
+++ b/src/geef_tree.erl
@@ -8,24 +8,29 @@
 
 -include("geef_records.hrl").
 
+-type tree() :: geef_obj:object(tree).
+-type entry() :: #geef_tree_entry{}.
+-export_type([tree/0, entry/0]).
+
+
 from_nif({ok, Mode, Type, Oid, Name}) ->
     {ok, #geef_tree_entry{mode=Mode, type=Type, id=#geef_oid{oid=Oid}, name=Name}};
 from_nif(Err = {error, _}) ->
     Err.
 
--spec get(geef_object(), iolist()) -> {ok, geef_tree_entry()} | {error, term()}.
+-spec get(tree(), iolist()) -> {ok, entry()} | {error, term()}.
 get(#geef_object{type=tree,handle=Handle}, Path) ->
     from_nif(geef_nif:tree_bypath(Handle, Path)).
 
--spec nth(geef_object(), non_neg_integer()) -> {ok, geef_tree_entry()} | {error, term()}.
+-spec nth(tree(), non_neg_integer()) -> {ok, entry()} | {error, term()}.
 nth(#geef_object{type=tree,handle=Handle}, Nth) ->
     from_nif(geef_nif:tree_nth(Handle, Nth)).
 
--spec count(geef_object()) -> non_neg_integer().
+-spec count(tree()) -> non_neg_integer().
 count(#geef_object{type=tree,handle=Handle}) ->
     geef_nif:tree_count(Handle).
 
--spec lookup(pid(), geef_oid() | iolist()) -> {ok, geef_object()} | {error, term()}.
+-spec lookup(pid(), geef_oid:oid() | iolist()) -> {ok, tree()} | {error, term()}.
 lookup(Repo, Id) ->
     geef_obj:lookup(Repo, Id, tree).