diff --git a/CHANGELOG.md b/CHANGELOG.md
index f232d5d8f..b6304393e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 2.26.4 [[#562](https://github.com/nerdvegas/rez/pull/562)] Fixed Regression in 2.24.0
+
+#### Addressed Issues
+
+* [#561](https://github.com/nerdvegas/rez/issues/561) timestamp not written to installed package
+
 ## 2.26.3 [[#560](https://github.com/nerdvegas/rez/pull/560)] Package.py permissions issue
 
 #### Addressed Issues
diff --git a/src/rez/utils/_version.py b/src/rez/utils/_version.py
index a5639f263..b46121070 100644
--- a/src/rez/utils/_version.py
+++ b/src/rez/utils/_version.py
@@ -1,7 +1,7 @@
 
 
 # Update this value to version up Rez. Do not place anything else in this file.
-_rez_version = "2.26.3"
+_rez_version = "2.26.4"
 
 try:
     from rez.vendor.version.version import Version
diff --git a/src/rezplugins/package_repository/filesystem.py b/src/rezplugins/package_repository/filesystem.py
index 6e7ee0c68..0e9525d14 100644
--- a/src/rezplugins/package_repository/filesystem.py
+++ b/src/rezplugins/package_repository/filesystem.py
@@ -1026,7 +1026,7 @@ def _remove_build_keys(obj):
                     package_data[key] = value
 
         # timestamp defaults to now if not specified
-        if "timestamp" not in package_data:
+        if not package_data.get("timestamp"):
             package_data["timestamp"] = int(time.time())
 
         # format version is always set