diff --git a/lib/config_upgrader.js b/lib/config_upgrader.js
index 9a4f39004..78cb8d9a6 100644
--- a/lib/config_upgrader.js
+++ b/lib/config_upgrader.js
@@ -269,7 +269,11 @@ class ConfigUpgrader {
       return report;
     });
 
-    return reports.reduce(function(a, b) { return a.concat([""]).concat(b); });
+    if (reports.length > 0) {
+      return reports.reduce(function(a, b) { return a.concat([""]).concat(b); });
+    } else {
+      return reports;
+    }
   }
 }
 
diff --git a/test/config_upgrater_test.js b/test/config_upgrater_test.js
index e6cba7123..1f1c356c0 100644
--- a/test/config_upgrater_test.js
+++ b/test/config_upgrater_test.js
@@ -55,6 +55,19 @@ describe("ConfigUpgrader", function() {
         });
       });
     });
+
+    it("doesn't care if there aren't any configs", function(done) {
+      temp.mkdir("code ", function(err, directory) {
+        if (err) { throw err; }
+
+        process.chdir(directory);
+
+        let report = ConfigUpgrader
+          .upgradeInstructions([directory + '/file.js'], directory);
+        expect(report).to.deep.eq([]);
+        done();
+      });
+    });
   });