diff --git a/src/pylorax/api/errors.py b/src/pylorax/api/errors.py
index 7509a25e..d6a90e8f 100644
--- a/src/pylorax/api/errors.py
+++ b/src/pylorax/api/errors.py
@@ -16,10 +16,17 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+# Returned from the API when either an invalid compose type is given, or not
+# compose type is given.
+BAD_COMPOSE_TYPE = "BadComposeType"
+
 # Returned from the API when ?limit= or ?offset= is given something that does
 # not convert into an integer.
 BAD_LIMIT_OR_OFFSET = "BadLimitOrOffset"
 
+# Returned from the API for any other error resulting from /compose failing.
+BUILD_FAILED = "BuildFailed"
+
 # Returned from the API when it expected a build to be in a state other than
 # what it currently is.  This most often happens when asking for results from
 # a build that is not yet done.
@@ -29,6 +36,10 @@ BUILD_IN_WRONG_STATE = "BuildInWrongState"
 # given that contains invalid characters.
 INVALID_NAME = "InvalidName"
 
+# Returned from the API when /compose is called without the POST body telling it
+# what to compose.
+MISSING_POST = "MissingPost"
+
 # Returned from the API when someone tries to modify an immutable system source.
 SYSTEM_SOURCE = "SystemSource"
 
diff --git a/src/pylorax/api/v0.py b/src/pylorax/api/v0.py
index 48e0824d..f362927e 100644
--- a/src/pylorax/api/v0.py
+++ b/src/pylorax/api/v0.py
@@ -1751,7 +1751,7 @@ def v0_api(api):
 
         errors = []
         if not compose:
-            return jsonify(status=False, errors=["Missing POST body"]), 400
+            return jsonify(status=False, errors=[{"id": MISSING_POST, "msg": "Missing POST body"}]), 400
 
         if "blueprint_name" not in compose:
             errors.append({"id": UNKNOWN_BLUEPRINT,"msg": "No 'blueprint_name' in the JSON request"})
@@ -1764,7 +1764,7 @@ def v0_api(api):
             branch = compose["branch"]
 
         if "compose_type" not in compose:
-            errors.append("No 'compose_type' in the JSON request")
+            errors.append({"id": BAD_COMPOSE_TYPE, "msg": "No 'compose_type' in the JSON request"})
         else:
             compose_type = compose["compose_type"]
 
@@ -1778,7 +1778,10 @@ def v0_api(api):
             build_id = start_build(api.config["COMPOSER_CFG"], api.config["DNFLOCK"], api.config["GITLOCK"],
                                    branch, blueprint_name, compose_type, test_mode)
         except Exception as e:
-            return jsonify(status=False, errors=[str(e)]), 400
+            if "Invalid compose type" in str(e):
+                return jsonify(status=False, errors=[{"id": BAD_COMPOSE_TYPE, "msg": str(e)}]), 400
+            else:
+                return jsonify(status=False, errors=[{"id": BUILD_FAILED, "msg": str(e)}]), 400
 
         return jsonify(status=True, build_id=build_id)
 
diff --git a/tests/pylorax/test_server.py b/tests/pylorax/test_server.py
index 2f10bb6b..53292736 100644
--- a/tests/pylorax/test_server.py
+++ b/tests/pylorax/test_server.py
@@ -780,7 +780,7 @@ class ServerTestCase(unittest.TestCase):
         data = json.loads(resp.data)
         self.assertNotEqual(data, None)
         self.assertEqual(data["status"], False, "Failed to fail to start test compose: %s" % data)
-        self.assertEqual(data["errors"], ["Invalid compose type (snakes), must be one of ['ext4-filesystem', 'live-iso', 'partitioned-disk', 'qcow2', 'tar']"],
+        self.assertEqual(data["errors"], [{"id": BAD_COMPOSE_TYPE, "msg": "Invalid compose type (snakes), must be one of ['ext4-filesystem', 'live-iso', 'partitioned-disk', 'qcow2', 'tar']"}],
                                          "Failed to get errors: %s" % data)
 
     def test_compose_03_status_fail(self):