diff --git a/.circleci/config.yml b/.circleci/config.yml
index 52ee02dc2..f0ef63d81 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -192,33 +192,6 @@ jobs:
             ./dev_scripts/env.py --distro ubuntu --version 23.10 run --dev \
                 bash -c 'cd dangerzone; poetry run make test'
 
-  ci-ubuntu-lunar:
-    machine:
-      image: ubuntu-2004:202111-01
-    steps:
-      - checkout
-      - run: *install-podman
-
-      - run:
-          name: Prepare cache directory
-          command: |
-            sudo mkdir -p /caches
-            sudo chown -R $USER:$USER /caches
-      - run: *calculate-cache-key
-      - restore_cache: *restore-cache
-      - run: *copy-image
-
-      - run:
-          name: Prepare Dangerzone environment
-          command: |
-            ./dev_scripts/env.py --distro ubuntu --version 23.04 build-dev
-
-      - run:
-          name: Run CI tests
-          command: |
-            ./dev_scripts/env.py --distro ubuntu --version 23.04 run --dev \
-                bash -c 'cd dangerzone; poetry run make test'
-
   ci-ubuntu-jammy:
     machine:
       image: ubuntu-2004:202111-01
@@ -453,18 +426,6 @@ jobs:
       - run: *copy-image
       - run: *build-deb
 
-  build-ubuntu-lunar:
-    docker:
-      - image: ubuntu:23.04
-    resource_class: medium+
-    steps:
-      - run: *install-dependencies-deb
-      - checkout
-      - run: *calculate-cache-key
-      - restore_cache: *restore-cache
-      - run: *copy-image
-      - run: *build-deb
-
   build-ubuntu-jammy:
     docker:
       - image: ubuntu:22.04
@@ -566,9 +527,6 @@ workflows:
       - ci-ubuntu-mantic:
           requires:
             - build-container-image
-      - ci-ubuntu-lunar:
-          requires:
-            - build-container-image
       - ci-ubuntu-jammy:
           requires:
             - build-container-image
@@ -593,9 +551,6 @@ workflows:
       - build-ubuntu-mantic:
           requires:
             - build-container-image
-      - build-ubuntu-lunar:
-          requires:
-            - build-container-image
       - build-ubuntu-jammy:
           requires:
             - build-container-image
diff --git a/.github/workflows/check_repos.yml b/.github/workflows/check_repos.yml
index 67c245036..40730405a 100644
--- a/.github/workflows/check_repos.yml
+++ b/.github/workflows/check_repos.yml
@@ -20,8 +20,6 @@ jobs:
         include:
           - distro: ubuntu
             version: "23.10"  # mantic
-          - distro: ubuntu
-            version: "23.04"  # lunar
           - distro: ubuntu
             version: "22.04"  # jammy
           - distro: ubuntu
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d98fb0f85..5206ac9e3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -92,9 +92,6 @@ jobs:
           - target: ubuntu-22.04
             distro: ubuntu
             version: "22.04"
-          - target: ubuntu-23.04
-            distro: ubuntu
-            version: "23.04"
           - target: ubuntu-23.10
             distro: ubuntu
             version: "23.10"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 05e14fd2b..346660a6e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,7 @@ since 0.4.1, and this project adheres to [Semantic Versioning](https://semver.or
 ### Removed
 
 - Removed timeouts ([issue #687](https://github.com/freedomofpress/dangerzone/issues/687))
+- Platform support: Drop Ubuntu 23.04 (Lunar Lobster), since it's end-of-life ([issue #705](https://github.com/freedomofpress/dangerzone/issues/705))
 
 ## Dangerzone 0.5.1
 
diff --git a/INSTALL.md b/INSTALL.md
index d619182f0..0b31ccd3b 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -10,7 +10,6 @@ an isolated environment. It will be installed automatically when installing Dang
 
 Dangerzone is available for:
 - Ubuntu 23.10 (mantic)
-- Ubuntu 23.04 (lunar)
 - Ubuntu 22.04 (jammy)
 - Ubuntu 20.04 (focal)
 - Debian 13 (trixie)
diff --git a/dev_scripts/env.py b/dev_scripts/env.py
index 72e8e3301..bb2b1fa15 100755
--- a/dev_scripts/env.py
+++ b/dev_scripts/env.py
@@ -574,9 +574,7 @@ def build_dev(self, show_dockerfile=DEFAULT_SHOW_DOCKERFILE):
                     DOCKERFILE_CONMON_UPDATE + DOCKERFILE_BUILD_DEV_DEBIAN_DEPS
                 )
             elif self.distro == "ubuntu" and self.version in (
-                "23.04",
                 "23.10",
-                "lunar",
                 "mantic",
             ):
                 install_deps = (
@@ -662,9 +660,7 @@ def build(
                 # package (see https://github.com/freedomofpress/dangerzone/issues/685)
                 install_deps = DOCKERFILE_CONMON_UPDATE + DOCKERFILE_BUILD_DEBIAN_DEPS
             elif self.distro == "ubuntu" and self.version in (
-                "23.04",
                 "23.10",
-                "lunar",
                 "mantic",
             ):
                 install_deps = DOCKERFILE_UBUNTU_REM_USER + DOCKERFILE_BUILD_DEBIAN_DEPS
diff --git a/dev_scripts/qa.py b/dev_scripts/qa.py
index c52d02681..84601c92d 100755
--- a/dev_scripts/qa.py
+++ b/dev_scripts/qa.py
@@ -887,11 +887,6 @@ class QAUbuntu2204(QADebianBased):
     VERSION = "22.04"
 
 
-class QAUbuntu2304(QADebianBased):
-    DISTRO = "ubuntu"
-    VERSION = "23.04"
-
-
 class QAUbuntu2310(QADebianBased):
     DISTRO = "ubuntu"
     VERSION = "23.10"