diff --git a/c_src/blob.c b/c_src/blob.c
index 2d6551b..01231a6 100644
--- a/c_src/blob.c
+++ b/c_src/blob.c
@@ -39,7 +39,7 @@ geef_blob_content(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		return atoms.error;
 
 	if (!enif_alloc_binary(len, &bin))
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(bin.data, content, len);
 
diff --git a/c_src/commit.c b/c_src/commit.c
index 901dcee..9114288 100644
--- a/c_src/commit.c
+++ b/c_src/commit.c
@@ -18,7 +18,7 @@ geef_commit_tree_id(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	id = git_commit_tree_id((git_commit *) obj->obj);
 
 	if (geef_oid_bin(&bin, id) < 0)
-		return atoms.error;
+		return geef_oom(env);
 
 	return enif_make_binary(env, &bin);
 }
diff --git a/c_src/geef.c b/c_src/geef.c
index 1b08a58..210077b 100644
--- a/c_src/geef.c
+++ b/c_src/geef.c
@@ -73,6 +73,9 @@ static int load(ErlNifEnv *env, void **priv, ERL_NIF_TERM load_info)
 	atoms.timesort    = enif_make_atom(env, "sort_time");
 	atoms.reversesort = enif_make_atom(env, "sort_reverse");
 	atoms.iterover    = enif_make_atom(env, "iterover");
+	/* Errors */
+	atoms.enomem = enif_make_atom(env, "enomem");
+	atoms.eunknown = enif_make_atom(env, "eunknown");
 
 	return 0;
 }
@@ -92,24 +95,34 @@ geef_error(ErlNifEnv *env)
 {
 	const git_error *error;
 	ErlNifBinary bin;
-	const char *message;
 	size_t len;
 
 	error = giterr_last();
-	if (error && error->message)
-		message = error->message;
-	else
-		message = "No message specified";
 
-	len = strlen(message);
+	if (!error)
+		return enif_make_tuple2(env, atoms.error, atoms.eunknown);
+
+	if (error->klass == GITERR_NOMEMORY)
+		return geef_oom(env);
+
+	if (!error->message)
+		return enif_make_tuple2(env, atoms.error, atoms.eunknown);
+
+	len = strlen(error->message);
 	if (!enif_alloc_binary(len, &bin))
-		return atoms.error;
+		return geef_oom(env);
 
-	memcpy(bin.data, message, len);
+	memcpy(bin.data, error->message, len);
 
 	return enif_make_tuple2(env, atoms.error, enif_make_binary(env, &bin));
 }
 
+ERL_NIF_TERM
+geef_oom(ErlNifEnv *env)
+{
+	return enif_make_tuple2(env, atoms.error, atoms.enomem);
+}
+
 static ErlNifFunc geef_funcs[] =
 {
 	{"repository_init", 2, geef_repository_init},
diff --git a/c_src/geef.h b/c_src/geef.h
index bd83944..acd7808 100644
--- a/c_src/geef.h
+++ b/c_src/geef.h
@@ -4,6 +4,7 @@
 #include "erl_nif.h"
 
 ERL_NIF_TERM geef_error(ErlNifEnv *env);
+ERL_NIF_TERM geef_oom(ErlNifEnv *env);
 
 typedef struct {
 	ERL_NIF_TERM ok;
@@ -21,6 +22,9 @@ typedef struct {
 	ERL_NIF_TERM timesort;
 	ERL_NIF_TERM reversesort;
 	ERL_NIF_TERM iterover;
+
+	ERL_NIF_TERM enomem;
+	ERL_NIF_TERM eunknown;
 } geef_atoms;
 
 extern geef_atoms atoms;
diff --git a/c_src/index.c b/c_src/index.c
index f84ca4a..4c1d10f 100644
--- a/c_src/index.c
+++ b/c_src/index.c
@@ -19,7 +19,7 @@ geef_index_new(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	index = enif_alloc_resource(geef_index_type, sizeof(geef_index));
 	if (!index)
-		return atoms.error;
+		return geef_oom(env);
 
 	if (git_index_new(&index->index) < 0)
 		return geef_error(env);
@@ -69,7 +69,7 @@ geef_index_write_tree(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		return geef_error(env);
 
 	if (geef_oid_bin(&bin, &id) < 0)
-		return atoms.error;
+		return geef_oom(env);
 
 	return enif_make_tuple2(env, atoms.ok, enif_make_binary(env, &bin));
 }
diff --git a/c_src/object.c b/c_src/object.c
index 1e40633..b90f064 100644
--- a/c_src/object.c
+++ b/c_src/object.c
@@ -64,7 +64,7 @@ geef_object_lookup(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	obj = enif_alloc_resource(geef_object_type, sizeof(geef_object));
 	if (!obj)
-		return atoms.error;
+		return geef_oom(env);
 
 	if (git_object_lookup(&obj->obj, repo->repo, &id, GIT_OBJ_ANY) < 0) {
 		enif_release_resource(obj);
@@ -94,7 +94,7 @@ geef_object_id(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	id = git_object_id(obj->obj);
 
 	if (geef_oid_bin(&bin, id) < 0)
-		return atoms.error;
+		return geef_oom(env);
 
 	return enif_make_tuple2(env, atoms.ok, enif_make_binary(env, &bin));
 }
diff --git a/c_src/oid.c b/c_src/oid.c
index 2e54ac3..a0cf889 100644
--- a/c_src/oid.c
+++ b/c_src/oid.c
@@ -26,7 +26,7 @@ geef_oid_fmt(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		return enif_make_badarg(env);
 
 	if (!enif_alloc_binary(GIT_OID_HEXSZ, &bin_out))
-		return atoms.error;
+		return geef_oom(env);
 
 	git_oid_fromraw(&id, bin.data);
 	git_oid_fmt((char *)bin_out.data, &id);
@@ -46,7 +46,7 @@ geef_oid_parse(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	git_oid_fromstrn(&id, (const char *)bin.data, bin.size);
 
 	if (geef_oid_bin(&bin_out, &id) < 0)
-		return atoms.error;
+		return geef_oom(env);
 
 	return enif_make_binary(env, &bin_out);
 }
diff --git a/c_src/reference.c b/c_src/reference.c
index bae2ce8..c408a20 100644
--- a/c_src/reference.c
+++ b/c_src/reference.c
@@ -38,7 +38,7 @@ geef_reference_list(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 on_error:
 	git_strarray_free(&array);
-	return atoms.error;
+	return geef_oom(env);
 }
 
 ERL_NIF_TERM
@@ -60,7 +60,7 @@ geef_reference_lookup(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	name = malloc(bin.size + 1);
 	if (!name)
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(name, bin.data, bin.size);
 	name[bin.size] = '\0';
@@ -142,7 +142,7 @@ geef_reference_glob(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	glob = malloc(bin.size + 1);
 	if (!glob)
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(glob, bin.data, bin.size);
 	glob[bin.size] = '\0';
@@ -173,7 +173,7 @@ geef_reference_target(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		id = git_reference_target(ref->ref);
 
 		if (geef_oid_bin(&bin, id) < 0)
-			return atoms.error;
+			return geef_oom(env);
 	} else {
 		const char *name;
 		size_t len;
@@ -182,7 +182,7 @@ geef_reference_target(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		len = strlen(name);
 
 		if (enif_alloc_binary(len, &bin) < 0)
-			return atoms.error;
+			return geef_oom(env);
 
 		memcpy(bin.data, name, len + 1);
 	}
@@ -206,7 +206,7 @@ geef_reference_to_id(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	name = malloc(bin.size + 1);
 	if (!name)
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(name, bin.data, bin.size);
 	name[bin.size] = '\0';
@@ -215,7 +215,7 @@ geef_reference_to_id(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		return geef_error(env);
 
 	if (geef_oid_bin(&bin, &id) < 0)
-		return atoms.error;
+		return geef_oom(env);
 
 	return enif_make_tuple2(env, atoms.ok, enif_make_binary(env, &bin));
 }
@@ -268,7 +268,7 @@ geef_reference_create(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	/* Allocate the extra byte for the NUL terminator */
 	if (!enif_realloc_binary(&name, name.size + 1))
-		return atoms.error;
+		return geef_oom(env);
 
 	name.data[name.size-1] = '\0';
 
@@ -283,7 +283,7 @@ geef_reference_create(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	} else if (enif_is_identical(argv[2], atoms.symbolic)) {
 		/* Allocate the extra byte for the NUL terminator */
 		if (!enif_realloc_binary(&target, target.size + 1))
-			return atoms.error;
+			return geef_oom(env);
 
 		target.data[target.size - 1] = '\0';
 		ptarget = (const char *) target.data;
diff --git a/c_src/repository.c b/c_src/repository.c
index cadd174..952cee1 100644
--- a/c_src/repository.c
+++ b/c_src/repository.c
@@ -32,7 +32,7 @@ geef_repository_init(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	path = malloc(bin.size + 1);
 	if (!path)
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(path, bin.data, bin.size);
 	path[bin.size] = '\0';
@@ -68,7 +68,7 @@ geef_repository_open(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	path = malloc(bin.size + 1);
 	if (!path)
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(path, bin.data, bin.size);
 	path[bin.size] = '\0';
@@ -100,7 +100,7 @@ geef_repository_discover(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	path = malloc(bin.size + 1);
 	if (!path)
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(path, bin.data, bin.size);
 	path[bin.size] = '\0';
@@ -108,7 +108,7 @@ geef_repository_discover(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	buffer_len = 256;
 	buffer = malloc(buffer_len);
 	if (!buffer)
-		return atoms.error;
+		return geef_oom(env);
 
 	while ((error = git_repository_discover(buffer, buffer_len, path, 0, NULL)) < 0 &&
 	       giterr_last()->klass == GITERR_REPOSITORY) {
@@ -118,7 +118,7 @@ geef_repository_discover(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		if (!tmp) {
 			free(path);
 			free(buffer);
-			return atoms.error;
+			return geef_oom(env);
 		}
 
 		buffer = tmp;
@@ -134,7 +134,7 @@ geef_repository_discover(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	buffer_len = strlen(buffer);
 	if (!enif_alloc_binary(buffer_len, &res_bin)) {
 		free(buffer);
-		return atoms.error;
+		return geef_oom(env);
 	}
 
 	memcpy(res_bin.data, buffer, buffer_len);
@@ -158,7 +158,7 @@ geef_repository_path(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	len = strlen(path);
 
 	if (!enif_alloc_binary(len, &bin))
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(bin.data, path, len);
 	return enif_make_binary(env, &bin);
@@ -182,7 +182,7 @@ geef_repository_workdir(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 	len = strlen(path);
 
 	if (!enif_alloc_binary(len, &bin))
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(bin.data, path, len);
 	return enif_make_binary(env, &bin);
@@ -266,7 +266,7 @@ geef_odb_write(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		return geef_error(env);
 
 	if (geef_oid_bin(&oid_bin, &oid) < 0)
-		return atoms.error;
+		return geef_oom(env);
 
 	return enif_make_tuple2(env, atoms.ok, enif_make_binary(env, &oid_bin));
 }
diff --git a/c_src/revwalk.c b/c_src/revwalk.c
index 9b13433..0a85f60 100644
--- a/c_src/revwalk.c
+++ b/c_src/revwalk.c
@@ -23,7 +23,7 @@ geef_revwalk_new(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	walk = enif_alloc_resource(geef_revwalk_type, sizeof(geef_revwalk));
 	if (!walk)
-		return atoms.error;
+		return geef_oom(env);
 
 	if (git_revwalk_new(&walk->walk, repo->repo) < 0) {
 		enif_release_resource(walk);
@@ -70,7 +70,7 @@ geef_revwalk_next(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 		return enif_make_badarg(env);
 
 	if (!enif_alloc_binary(GIT_OID_RAWSZ, &bin))
-		return atoms.error;
+		return geef_oom(env);
 
 	if ((error = git_revwalk_next((git_oid *)bin.data, walk->walk)) < 0) {
 		if (error == GIT_ITEROVER)
diff --git a/c_src/tree.c b/c_src/tree.c
index 1f7cfca..7062425 100644
--- a/c_src/tree.c
+++ b/c_src/tree.c
@@ -24,11 +24,11 @@ static ERL_NIF_TERM tree_entry_to_term(ErlNifEnv *env, const git_tree_entry *ent
 	ErlNifBinary name, oid;
 
 	if (geef_oid_bin(&oid, git_tree_entry_id(entry)) < 0)
-		return atoms.error;
+		return geef_oom(env);
 
 	if (geef_string_bin(&name, git_tree_entry_name(entry)) < 0) {
 		enif_release_binary(&name);
-		return atoms.error;
+		return geef_oom(env);
 	}
 
 	return enif_make_tuple5(env, atoms.ok, enif_make_int(env, git_tree_entry_filemode(entry)),
@@ -54,7 +54,7 @@ geef_tree_bypath(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 
 	path = malloc(bin.size + 1);
 	if (!path)
-		return atoms.error;
+		return geef_oom(env);
 
 	memcpy(path, bin.data, bin.size);
 	path[bin.size] = '\0';