diff --git a/demo/Gemfile.lock b/demo/Gemfile.lock
index c8a7ac61eb..3fdb98a6f1 100644
--- a/demo/Gemfile.lock
+++ b/demo/Gemfile.lock
@@ -1,3 +1,22 @@
+GIT
+  remote: https://github.com/getkuby/kuby-core.git
+  revision: f9a2a7f20daee8b95b6ce6b4a1b994fc7531ba7c
+  ref: f9a2a7f20daee8b95b6ce6b4a1b994fc7531ba7c
+  specs:
+    kuby-core (0.20.1)
+      colorize (~> 0.8)
+      docker-remote (~> 0.8)
+      gli (~> 2.21)
+      helm-cli (~> 0.3)
+      krane (~> 2.0)
+      kube-dsl (~> 0.7)
+      kubernetes-cli (~> 0.4)
+      kuby-cert-manager (~> 0.4)
+      kuby-crdb (~> 0.2)
+      railties (>= 5.1)
+      rake
+      rouge (~> 3.0)
+
 PATH
   remote: ..
   specs:
@@ -175,19 +194,6 @@ GEM
       kube-dsl (~> 0.1)
     kuby-cert-manager (0.4.0)
       kube-dsl (~> 0.1)
-    kuby-core (0.20.1)
-      colorize (~> 0.8)
-      docker-remote (~> 0.8)
-      gli (~> 2.21)
-      helm-cli (~> 0.3)
-      krane (~> 2.0)
-      kube-dsl (~> 0.7)
-      kubernetes-cli (~> 0.4)
-      kuby-cert-manager (~> 0.4)
-      kuby-crdb (~> 0.2)
-      railties (>= 5.1)
-      rake
-      rouge (~> 3.0)
     kuby-crdb (0.3.0)
       kube-dsl (~> 0.7)
     kuby-kind (0.2.3)
@@ -366,7 +372,7 @@ DEPENDENCIES
   hotwire-livereload (~> 1.4)
   kind-rb (~> 0.1)
   kuby-azure (~> 0.4.0)
-  kuby-core (~> 0.20)
+  kuby-core!
   kuby-kind (~> 0.2)
   listen
   lookbook (~> 2.3.2)
diff --git a/demo/gemfiles/kuby.gemfile b/demo/gemfiles/kuby.gemfile
index 4762677b98..032860f867 100644
--- a/demo/gemfiles/kuby.gemfile
+++ b/demo/gemfiles/kuby.gemfile
@@ -1,6 +1,6 @@
 source "https://rubygems.org"
 
-gem "kuby-core", "~> 0.20"
+gem "kuby-core", github: "getkuby/kuby-core", ref: "f9a2a7f20daee8b95b6ce6b4a1b994fc7531ba7c" # "~> 0.20"
 gem "kuby-azure", "~> 0.4.0"
 gem "kuby-kind", "~> 0.2"
 gem "kind-rb", "~> 0.1"
diff --git a/demo/gemfiles/kuby.gemfile.lock b/demo/gemfiles/kuby.gemfile.lock
index 30cf56cc96..4b41f8f525 100644
--- a/demo/gemfiles/kuby.gemfile.lock
+++ b/demo/gemfiles/kuby.gemfile.lock
@@ -1,3 +1,22 @@
+GIT
+  remote: https://github.com/getkuby/kuby-core.git
+  revision: f9a2a7f20daee8b95b6ce6b4a1b994fc7531ba7c
+  ref: f9a2a7f20daee8b95b6ce6b4a1b994fc7531ba7c
+  specs:
+    kuby-core (0.20.1)
+      colorize (~> 0.8)
+      docker-remote (~> 0.8)
+      gli (~> 2.21)
+      helm-cli (~> 0.3)
+      krane (~> 2.0)
+      kube-dsl (~> 0.7)
+      kubernetes-cli (~> 0.4)
+      kuby-cert-manager (~> 0.4)
+      kuby-crdb (~> 0.2)
+      railties (>= 5.1)
+      rake
+      rouge (~> 3.0)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -123,19 +142,6 @@ GEM
       kube-dsl (~> 0.1)
     kuby-cert-manager (0.4.0)
       kube-dsl (~> 0.1)
-    kuby-core (0.20.1)
-      colorize (~> 0.8)
-      docker-remote (~> 0.8)
-      gli (~> 2.21)
-      helm-cli (~> 0.3)
-      krane (~> 2.0)
-      kube-dsl (~> 0.7)
-      kubernetes-cli (~> 0.4)
-      kuby-cert-manager (~> 0.4)
-      kuby-crdb (~> 0.2)
-      railties (>= 5.1)
-      rake
-      rouge (~> 3.0)
     kuby-crdb (0.2.0)
       kube-dsl (~> 0.7)
     kuby-kind (0.2.1)
@@ -228,7 +234,7 @@ PLATFORMS
 DEPENDENCIES
   kind-rb (~> 0.1)
   kuby-azure (~> 0.4.0)
-  kuby-core (~> 0.20)
+  kuby-core!
   kuby-kind (~> 0.2)
   pry-byebug