diff --git a/Dockerfile b/Dockerfile
index 9b6c8df..c0ab08a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,6 +17,7 @@ RUN \
  apk add --no-cache \
 	curl \
 	php7 \
+	php7-ctype \
 	php7-gd \
 	php7-pdo \
 	php7-pdo_sqlite \
diff --git a/Dockerfile.aarch64 b/Dockerfile.aarch64
index ef6a95f..7f35f95 100644
--- a/Dockerfile.aarch64
+++ b/Dockerfile.aarch64
@@ -17,6 +17,7 @@ RUN \
  apk add --no-cache \
 	curl \
 	php7 \
+	php7-ctype \
 	php7-gd \
 	php7-pdo \
 	php7-pdo_sqlite \
diff --git a/Dockerfile.armhf b/Dockerfile.armhf
index 3071100..1b6ef3f 100644
--- a/Dockerfile.armhf
+++ b/Dockerfile.armhf
@@ -17,6 +17,7 @@ RUN \
  apk add --no-cache \
 	curl \
 	php7 \
+	php7-ctype \
 	php7-gd \
 	php7-pdo \
 	php7-pdo_sqlite \
diff --git a/readme-vars.yml b/readme-vars.yml
index bfbdf2f..d56556d 100644
--- a/readme-vars.yml
+++ b/readme-vars.yml
@@ -39,6 +39,7 @@ app_setup_block: |
 
 # changelog
 changelogs:
+  - { date: "22.12.20:", desc: "Add 'ctype' PHP extension." }
   - { date: "01.06.20:", desc: "Rebasing to alpine 3.12." }
   - { date: "19.12.19:", desc: "Rebasing to alpine 3.11." }
   - { date: "22.09.19:", desc: "Add 'gd' PHP extension." }