diff --git a/Gemfile b/Gemfile
index c37b7ad3a..c7207bc94 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,4 +14,4 @@ gem 'benchmark'
 gem 'mutex_m'
 gem 'nkf'
 gem 'xcodeproj', '< 1.26.0'
-gem 'concurrent-ruby', '< 1.3.4'
+gem 'concurrent-ruby', '< 1.3.8'
diff --git a/Gemfile.lock b/Gemfile.lock
index cd7e381f3..d72924014 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -62,7 +62,7 @@ GEM
       netrc (~> 0.11)
     cocoapods-try (1.2.0)
     colored2 (3.1.2)
-    concurrent-ruby (1.3.3)
+    concurrent-ruby (1.3.7)
     connection_pool (3.0.2)
     drb (2.2.3)
     escape (0.0.4)
@@ -95,6 +95,7 @@ GEM
     nanaimo (0.3.0)
     nap (1.1.0)
     netrc (0.11.0)
+    nkf (0.3.0)
     public_suffix (4.0.7)
     rexml (3.4.4)
     ruby-macho (2.5.1)
@@ -130,9 +131,10 @@ DEPENDENCIES
   benchmark
   bigdecimal
   cocoapods (>= 1.13, != 1.15.1, != 1.15.0)
-  concurrent-ruby (< 1.3.4)
+  concurrent-ruby (< 1.3.8)
   logger
   mutex_m
+  nkf
   xcodeproj (< 1.26.0)
 
 RUBY VERSION