diff --git a/tools/bump.sh b/tools/bump.sh
index 3c0390d..0a09582 100755
--- a/tools/bump.sh
+++ b/tools/bump.sh
@@ -1,13 +1,17 @@
 #!/usr/bin/env bash
 #
-# Bump latest version to
+# 1. Bump latest version number to files:
 #   - _sass/jekyll-theme-chirpy.scss
 #   - assets/js/.copyright.js
-#   - assets/js/dist/*.js
+#   - assets/js/dist/*.js (will be built by gulp later)
 #   - jekyll-theme-chirpy.gemspec
 #   - package.json
 #
-# Required: gulp
+# 2. Create a git-tag
+#
+# 3. Build a rubygem package
+#
+# Requires: gulp, rubygem
 
 set -eu
 
@@ -20,7 +24,28 @@ GEM_SPEC="jekyll-theme-chirpy.gemspec"
 
 NODE_META="package.json"
 
-bump_assets() {
+_check_src() {
+  if [[ ! -f $1 && ! -d $1 ]]; then
+    echo -e "Error: missing file \"$1\"!\n"
+    exit -1
+  fi
+}
+
+check() {
+  if [[ -n $(git status . -s) ]]; then
+    echo "Warning: commit unstaged files first, and then run this tool againt."
+    exit -1
+  fi
+
+  for i in "${!ASSETS[@]}"; do
+    _check_src "${ASSETS[$i]}"
+  done
+
+  _check_src "$NODE_META"
+  _check_src "$GEM_SPEC"
+}
+
+_bump_assets() {
   _version="$1"
   for i in "${!ASSETS[@]}"; do
     sed -i "s/v[[:digit:]]\.[[:digit:]]\.[[:digit:]]/v$_version/" "${ASSETS[$i]}"
@@ -29,20 +54,20 @@ bump_assets() {
   gulp
 }
 
-bump_gemspec() {
+_bump_gemspec() {
   sed -i "s/[[:digit:]]\.[[:digit:]]\.[[:digit:]]/$1/" "$GEM_SPEC"
 }
 
-bump_node() {
+_bump_node() {
   sed -i \
     "s,[\"]version[\"]: [\"][[:digit:]]\.[[:digit:]]\.[[:digit:]][\"],\"version\": \"$1\"," \
     $NODE_META
 }
 
 bump() {
-  bump_assets "$1"
-  bump_gemspec "$1"
-  bump_node "$1"
+  _bump_assets "$1"
+  _bump_gemspec "$1"
+  _bump_node "$1"
 
   if [[ -n $(git status . -s) ]]; then
     git add .
@@ -50,11 +75,12 @@ bump() {
   fi
 }
 
+build_gem() {
+  gem build "$GEM_SPEC"
+}
+
 main() {
-  if [[ -n $(git status . -s) ]]; then
-    echo "Warning: commit unstaged files first, and then run this tool againt."
-    exit -1
-  fi
+  check
 
   _latest_tag="$(git describe --tags --abbrev=0)"
 
@@ -69,15 +95,18 @@ main() {
       exit -1
     fi
 
-    echo "Bump version to $_version"
+    echo -e "Bump version to $_version\n"
     bump "$_version"
 
-    echo "Create tag v$_version"
+    echo -e "Create tag v$_version\n"
     git tag "v$_version"
 
+    build_gem
+
   else
 
     echo "Error: Illegal version number: '$_version'"
+
   fi
 }
 
diff --git a/tools/gem.sh b/tools/gem.sh
deleted file mode 100755
index 0ef0f38..0000000
--- a/tools/gem.sh
+++ /dev/null
@@ -1,22 +0,0 @@
-#!/usr/bin/env bash
-#
-# Create a ruby-gem pakcage with doc
-#
-# Required: rubygem, yard
-
-set -eu
-
-GEM_CONFIG="./jekyll-theme-chirpy.gemspec"
-
-if [[ ! -f $GEM_CONFIG ]]; then
-  echo "Error: .gemspec file not found!"
-  exit -1
-fi
-
-if [[ -d doc ]]; then
-  rm -rf doc
-fi
-
-yard doc
-
-gem build "$GEM_CONFIG"