diff --git a/Gemfile.lock b/Gemfile.lock
index 602fb4b..2827e00 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -4,7 +4,7 @@ PATH
     rswag_schema_export (0.3.0)
       aws-sdk-s3 (~> 1)
       azure-storage-blob (>= 1.1, < 3.0)
-      slack-notifier (~> 2.3.2)
+      slack-notifier (>= 2.3.2, < 2.5.0)
       swagger-diff (~> 1.1.2)
 
 GEM
@@ -146,7 +146,7 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.2)
-    slack-notifier (2.3.2)
+    slack-notifier (2.4.0)
     swagger-diff (1.1.2)
       json-schema (~> 2.6)
       rspec-expectations (~> 3.3)
diff --git a/rswag_schema_export.gemspec b/rswag_schema_export.gemspec
index 6cdf697..698cdcb 100644
--- a/rswag_schema_export.gemspec
+++ b/rswag_schema_export.gemspec
@@ -22,7 +22,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency "aws-sdk-s3", "~> 1"
   spec.add_dependency "azure-storage-blob", ">= 1.1", "< 3.0"
   spec.add_dependency "swagger-diff", "~> 1.1.2"
-  spec.add_dependency "slack-notifier", "~> 2.3.2"
+  spec.add_dependency "slack-notifier", ">= 2.3.2", "< 2.5.0"
 
   spec.add_development_dependency "bundler", "~> 2.0"
   spec.add_development_dependency "pry"