diff --git a/src/progress.js b/src/progress.js
index 8c486066f..f8d9d4680 100644
--- a/src/progress.js
+++ b/src/progress.js
@@ -22,7 +22,7 @@ var progress = {
 
 // We use -1 for percentage to indicate errors
 function set(tag, percent, message) {
-    assert(tag === exports.UPDATE || tag === exports.BACKUP);
+    assert.strictEqual(typeof tag, 'string');
     assert.strictEqual(typeof percent, 'number');
     assert.strictEqual(typeof message, 'string');
 
@@ -35,7 +35,7 @@ function set(tag, percent, message) {
 }
 
 function clear(tag) {
-    assert(tag === exports.UPDATE || tag === exports.BACKUP);
+    assert.strictEqual(typeof tag, 'string');
 
     progress[tag] = null;