diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 97b80a530..23a583af1 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -8,10 +8,11 @@ on:
 jobs:
   build-php:
     name: Prepare PHP
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.image }}
 
     strategy:
       matrix:
+        image: [ubuntu-20.04]
         php: [7.4.13]
 
     steps:
@@ -21,7 +22,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: "./bin"
-          key: "php-build-generic-${{ matrix.php }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
+          key: "php-build-generic-${{ matrix.php }}-${{ matrix.image }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
 
       - name: Compile PHP
         if: steps.php-build-cache.outputs.cache-hit != 'true'
@@ -30,11 +31,12 @@ jobs:
   phpstan:
     name: PHPStan analysis
     needs: build-php
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.image }}
 
     strategy:
       fail-fast: false
       matrix:
+        image: [ubuntu-20.04]
         php: [7.4.13]
 
     steps:
@@ -45,7 +47,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: "./bin"
-          key: "php-build-generic-${{ matrix.php }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
+          key: "php-build-generic-${{ matrix.php }}-${{ matrix.image }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
 
       - name: Kill build on PHP build cache miss (should never happen)
         if: steps.php-build-cache.outputs.cache-hit != 'true'
@@ -76,10 +78,11 @@ jobs:
   phpunit:
     name: PHPUnit tests
     needs: build-php
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.image }}
     strategy:
       fail-fast: false
       matrix:
+        image: [ubuntu-20.04]
         php: [7.4.13]
 
     steps:
@@ -90,7 +93,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: "./bin"
-          key: "php-build-generic-${{ matrix.php }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
+          key: "php-build-generic-${{ matrix.php }}-${{ matrix.image }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
 
       - name: Kill build on PHP build cache miss (should never happen)
         if: steps.php-build-cache.outputs.cache-hit != 'true'
@@ -121,10 +124,11 @@ jobs:
   integration:
     name: Integration tests
     needs: build-php
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.image }}
     strategy:
       fail-fast: false
       matrix:
+        image: [ubuntu-20.04]
         php: [7.4.13]
 
     steps:
@@ -137,7 +141,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: "./bin"
-          key: "php-build-generic-${{ matrix.php }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
+          key: "php-build-generic-${{ matrix.php }}-${{ matrix.image }}-${{ hashFiles('./tests/gh-actions/build.sh') }}"
 
       - name: Kill build on PHP build cache miss (should never happen)
         if: steps.php-build-cache.outputs.cache-hit != 'true'
diff --git a/changelogs/3.17.md b/changelogs/3.17.md
index 277c10ee0..6c78eaafe 100644
--- a/changelogs/3.17.md
+++ b/changelogs/3.17.md
@@ -32,3 +32,12 @@ Plugin developers should **only** update their required API to this version if y
 - Improved performance of region header validation in Region-based worlds (indirect improvement to chunk loading performance).
 - Fixed some PHP 8.0 language-level compatibility issues.
 - Source installations will now exit with an error when Composer dependencies are not in sync with the current Git revision. Now, it's required to run `composer install` after every git pull to make sure the correct dependency versions are installed.
+
+# 3.17.4
+- Removed `readline` support. This hasn't been maintained for many years, never worked correctly, and isn't thread-safe in any case.
+- Fixed false-positives of region corruption in Region-based worlds (outdated file stat cache).
+- Fixed more deprecation warnings on PHP 8.0 (optional parameter before required).
+- `CraftItemEvent->getInputs()` now returns a list starting at offset 0, instead of random offsets. (Note that the contents still won't be ordered.)
+- `CraftItemEvent->getOutputs()` now returns a list starting at offset 0, instead of random offsets. (Note that the contents still won't be ordered.)
+- Fixed a bug that broke synchronized building, bridging, towering and more.
+- Objects in memory dumps no longer show inherited properties multiple times.
diff --git a/src/world/format/io/region/RegionLoader.php b/src/world/format/io/region/RegionLoader.php
index b2aa71c5a..1aa06812f 100644
--- a/src/world/format/io/region/RegionLoader.php
+++ b/src/world/format/io/region/RegionLoader.php
@@ -34,7 +34,6 @@ use function ceil;
 use function chr;
 use function clearstatcache;
 use function fclose;
-use function feof;
 use function file_exists;
 use function filesize;
 use function fopen;
@@ -45,13 +44,11 @@ use function fwrite;
 use function is_resource;
 use function ksort;
 use function max;
-use function ord;
 use function str_pad;
 use function str_repeat;
 use function stream_set_read_buffer;
 use function stream_set_write_buffer;
 use function strlen;
-use function substr;
 use function time;
 use function touch;
 use function unpack;