diff --git a/api/lock_api.go b/api/lock_api.go
index 8c2c2a53..8ed73724 100644
--- a/api/lock_api.go
+++ b/api/lock_api.go
@@ -185,5 +185,5 @@ type LockList struct {
 	// Err populates any error that was encountered during the search. If no
 	// error was encountered and the operation was succesful, then a value
 	// of nil will be passed here.
-	Err error `json:"error,omitempty"`
+	Err string `json:"error,omitempty"`
 }
diff --git a/api/lock_api_test.go b/api/lock_api_test.go
index da049401..28c319d8 100644
--- a/api/lock_api_test.go
+++ b/api/lock_api_test.go
@@ -152,3 +152,44 @@ func TestUnlockResponseDoesNotAllowLockAndError(t *testing.T) {
 		Err: "some-error",
 	})
 }
+
+func TestLockListWithLocks(t *testing.T) {
+	schema.Validate(t, schema.LockListSchema, &api.LockList{
+		Locks: []api.Lock{
+			api.Lock{Id: "foo"},
+			api.Lock{Id: "bar"},
+		},
+	})
+}
+
+func TestLockListWithNoResults(t *testing.T) {
+	schema.Validate(t, schema.LockListSchema, &api.LockList{
+		Locks: []api.Lock{},
+	})
+}
+
+func TestLockListWithNextCursor(t *testing.T) {
+	schema.Validate(t, schema.LockListSchema, &api.LockList{
+		Locks: []api.Lock{
+			api.Lock{Id: "foo"},
+			api.Lock{Id: "bar"},
+		},
+		NextCursor: "baz",
+	})
+}
+
+func TestLockListWithError(t *testing.T) {
+	schema.Validate(t, schema.LockListSchema, &api.LockList{
+		Err: "some error",
+	})
+}
+
+func TestLockListWithErrorAndLocks(t *testing.T) {
+	schema.Refute(t, schema.LockListSchema, &api.LockList{
+		Locks: []api.Lock{
+			api.Lock{Id: "foo"},
+			api.Lock{Id: "bar"},
+		},
+		Err: "this isn't possible!",
+	})
+}
diff --git a/api/schema/lock_list_schema.json b/api/schema/lock_list_schema.json
new file mode 100644
index 00000000..e2fa6a36
--- /dev/null
+++ b/api/schema/lock_list_schema.json
@@ -0,0 +1,65 @@
+{
+    "$schema": "http://json-schema.org/draft-04/schema#",
+
+    "type": "object",
+	"oneOf": [
+        {
+            "properties": {
+                "locks": {
+                    "type": "array",
+                    "items": {
+                        "type": "object",
+                        "properties": {
+                            "id": {
+                                "type": "string"
+                            },
+                            "path": {
+                                "type": "string"
+                            },
+                            "committer": {
+                                "type": "object",
+                                "properties": {
+                                    "name": {
+                                        "type": "string"
+                                    },
+                                    "email": {
+                                        "type": "string"
+                                    }
+                                },
+                                "required": ["name", "email"]
+                            },
+                            "commit_sha": {
+                                "type": "string"
+                            },
+                            "locked_at": {
+                                "type": "string"
+                            },
+                            "unlocked_at": {
+                                "type": "string"
+                            }
+                        },
+                        "required": ["id", "path", "commit_sha", "locked_at"],
+                        "additionalItems": false
+                    }
+                },
+                "next_cursor": {
+                    "type": "string"
+                }
+            },
+            "additionalProperties": false,
+            "required": ["locks"]
+        },
+        {
+            "properties": {
+                "locks": {
+                    "type": "null"
+                },
+                "error": {
+                    "type": "string"
+                }
+            },
+            "additionalProperties": false,
+            "required": ["error"]
+        }
+    ]
+}
diff --git a/api/schema/schemas.go b/api/schema/schemas.go
index fa3aaeae..e4e90f6d 100644
--- a/api/schema/schemas.go
+++ b/api/schema/schemas.go
@@ -16,6 +16,7 @@
 package schema
 
 const (
+	LockListSchema       = "lock_list_schema.json"
 	LockRequestSchema    = "lock_request_schema.json"
 	LockResponseSchema   = "lock_response_schema.json"
 	UnlockResponseSchema = "unlock_response_schema.json"