diff --git a/.github/workflows/build-lint-and-test.yml b/.github/workflows/build-lint-and-test.yml
index c06fc7bb..615ddbc0 100644
--- a/.github/workflows/build-lint-and-test.yml
+++ b/.github/workflows/build-lint-and-test.yml
@@ -25,6 +25,9 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+      
+      - name: Update apt cache
+        run: sudo apt-get update -y
 
       - name: Install dependencies
         run: make install-build-dependencies
@@ -66,6 +69,9 @@ jobs:
         with:
           python-version: '3.11'
 
+      - name: Update apt cache
+        run: sudo apt-get update -y
+
       - name: Install CCM
         run: |
           make install-ccm-if-missing
@@ -165,6 +171,9 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: '3.11'
+          
+      - name: Update apt cache
+        run: sudo apt-get update -y
 
       - name: Install CCM
         run: make install-ccm-if-missing
diff --git a/.github/workflows/pkg.yml b/.github/workflows/pkg.yml
index 97cde88b..b9946199 100644
--- a/.github/workflows/pkg.yml
+++ b/.github/workflows/pkg.yml
@@ -60,5 +60,8 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
       
+      - name: Update apt cache
+        run: sudo apt-get update -y
+      
       - name: Build deb package for ${{ matrix.dist-version }}
         run: ./dist/debian/build_deb.sh --target ${{ matrix.dist-version }}
diff --git a/Makefile b/Makefile
index 7c2d6b34..218fb4c4 100644
--- a/Makefile
+++ b/Makefile
@@ -77,6 +77,8 @@ clean:
 
 update-apt-cache-if-needed:
 	@{\
+		# It searches for a file that is at most one day old.\
+		# If there is no such file, executes apt update.\
 		@sudo find /var/cache/apt -type f -mtime -1 2>/dev/null | grep -c "" 2>/dev/null | grep 0 >/dev/null 2>&1 || (\
 			echo "Apt cache is outdated, update it.";\
 			sudo apt-get update || true;\