diff --git a/Gax/composer.json b/Gax/composer.json
index 9e90d747eae..0a90bf0a50a 100644
--- a/Gax/composer.json
+++ b/Gax/composer.json
@@ -24,7 +24,7 @@
         "phpspec/prophecy-phpunit": "^2.1",
         "phpstan/phpstan": "^2.0",
         "google/cloud-tools": "^0.16.1",
-        "webmozart/assert": "^1.11.0"
+        "webmozart/assert": "^2.0.0"
     },
     "extra": {
         "component": {
diff --git a/composer.json b/composer.json
index 10d3a0f43f1..0dee3f9cb2f 100644
--- a/composer.json
+++ b/composer.json
@@ -89,7 +89,7 @@
         "dms/phpunit-arraysubset-asserts": "^0.5.0",
         "symfony/process": "^6.4",
         "kelvinmo/simplejwt": "^1.1.0",
-        "webmozart/assert": "^1.11.0"
+        "webmozart/assert": "^2.0.0"
     },
     "replace": {
         "google/access-context-manager": "1.2.1",