diff --git a/ruby_event_store-browser/Gemfile b/ruby_event_store-browser/Gemfile
index aefa9beab3..82efbf4af8 100644
--- a/ruby_event_store-browser/Gemfile
+++ b/ruby_event_store-browser/Gemfile
@@ -10,7 +10,7 @@ gem "ruby_event_store", path: ".."
 gem "rack-test"
 gem "capybara", "~> 3.35"
 gem "json-schema"
-gem "rack", "~> 3.0"
+gem "rack", "~> 3.0", "< 3.1.0"
 gem "webrick"
 gem "cuprite"
 gem "rackup"
diff --git a/ruby_event_store-browser/Gemfile.lock b/ruby_event_store-browser/Gemfile.lock
index 308b46a1e8..d4d8660d5e 100644
--- a/ruby_event_store-browser/Gemfile.lock
+++ b/ruby_event_store-browser/Gemfile.lock
@@ -64,7 +64,7 @@ GEM
       racc
     public_suffix (5.0.5)
     racc (1.8.0)
-    rack (3.1.3)
+    rack (3.0.11)
     rack-test (2.1.0)
       rack (>= 1.3)
     rackup (2.1.0)
@@ -110,7 +110,7 @@ DEPENDENCIES
   mutant (= 0.12.0)
   mutant-minitest (= 0.12.0)
   mutant-rspec (= 0.12.0)
-  rack (~> 3.0)
+  rack (~> 3.0, < 3.1.0)
   rack-test
   rackup
   rake (>= 10.0)