diff --git a/CHANGELOG.md b/CHANGELOG.md
index 23db9b1a..b620101c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,9 @@
 - Added feature create new empty file ([pybricks-code#771]).
 - Added sponsor button ([support#719]).
 
+### Fixed
+- Fixed firmware checksum validation when checksum === 0.
+
 [pybricks-code#771]: https://github.com/pybricks/pybricks-code/issues/771
 [support#719]: https://github.com/pybricks/support/issues/719
 
diff --git a/src/firmware/sagas.ts b/src/firmware/sagas.ts
index 957d8eba..6ef85cc5 100644
--- a/src/firmware/sagas.ts
+++ b/src/firmware/sagas.ts
@@ -309,7 +309,7 @@ function* loadFirmware(
             }
         })();
 
-        if (!checksum) {
+        if (checksum === undefined) {
             // FIXME: we should return error/throw instead
             yield* put(
                 didFailToFinish(
@@ -352,7 +352,7 @@ function* loadFirmware(
         }
     })();
 
-    if (!checksum) {
+    if (checksum === undefined) {
         // FIXME: we should return error/throw instead
         yield* put(
             didFailToFinish(