diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ded9b68d..b661dea3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -70,11 +70,11 @@ jobs:
       # done first.
       - name: Build 32-bit
         if: ${{ matrix.os == 'ubuntu-latest' && matrix.build_system == 'autotools' }}
-        run: ./build-aux/ci_build.sh -b autotools -p build -f "-m32"
+        run: ./build-aux/ci_build.bash -b autotools -p build -f "-m32"
       - name: Test 32-bit
         if: ${{ matrix.os == 'ubuntu-latest' && matrix.build_system == 'autotools' }}
         run: |
-            ./build-aux/ci_build.sh -b autotools -p test -f "-m32" -n 32_bit
+            ./build-aux/ci_build.bash -b autotools -p test -f "-m32" -n 32_bit
             cd ../xz_build && make distclean
 
       # The sandbox must be disabled because it will prevent access to
@@ -82,78 +82,78 @@ jobs:
       # instrumentation.
       - name: Build with -fsanitize=address,undefined
         if: ${{ matrix.os == 'ubuntu-latest' && matrix.build_system == 'autotools' }}
-        run: ./build-aux/ci_build.sh -b autotools -p build -f "-fsanitize=address,undefined" -d sandbox
+        run: ./build-aux/ci_build.bash -b autotools -p build -f "-fsanitize=address,undefined" -d sandbox
       - name: Test with -fsanitize=address,undefined
         if: ${{ matrix.os == 'ubuntu-latest' && matrix.build_system == 'autotools' }}
         run: |
             export UBSAN_OPTIONS=print_stacktrace=1:halt_on_error=1
-            ./build-aux/ci_build.sh -b autotools -p test -f "-fsanitize=address,undefined" -d sandbox
+            ./build-aux/ci_build.bash -b autotools -p test -f "-fsanitize=address,undefined" -d sandbox
             cd ../xz_build && make distclean
 
       - name: Build with Valgrind
         if: ${{ matrix.os == 'ubuntu-latest' && matrix.build_system == 'autotools' }}
-        run: ./build-aux/ci_build.sh -b autotools -p build -d sandbox
+        run: ./build-aux/ci_build.bash -b autotools -p build -d sandbox
       - name: Test with Valgrind
         if: ${{ matrix.os == 'ubuntu-latest' && matrix.build_system == 'autotools' }}
         run: |
-            ./build-aux/ci_build.sh -b autotools -p test -d sandbox -w "valgrind --quiet --trace-children=yes --exit-on-first-error=yes --error-exitcode=1"
+            ./build-aux/ci_build.bash -b autotools -p test -d sandbox -w "valgrind --quiet --trace-children=yes --exit-on-first-error=yes --error-exitcode=1"
             cd ../xz_build && make distclean
 
       - name: Build with musl libc
         if: ${{ matrix.os == 'ubuntu-latest'}}
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -p build -m "/usr/bin/musl-gcc"
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -p build -m "/usr/bin/musl-gcc"
       - name: Test with musl libc
         if: ${{ matrix.os == 'ubuntu-latest'}}
         run: |
-            ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -p test -m "/usr/bin/musl-gcc"
+            ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -p test -m "/usr/bin/musl-gcc"
       - name: Clean up musl libc run
         if: ${{ matrix.os == 'ubuntu-latest' && matrix.build_system == 'autotools' }}
         run: cd ../xz_build && make distclean
 
       - name: Build with full features
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -p build
       - name: Test with full features
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -p test -n full_features
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -p test -n full_features
 
       - name: Build without encoders
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d encoders,shared -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d encoders,shared -p build
       - name: Test without encoders
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d encoders,shared -p test -n no_encoders
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d encoders,shared -p test -n no_encoders
 
       - name: Build without decoders
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d decoders,shared -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d decoders,shared -p build
       - name: Test without decoders
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d decoders,shared -p test -n no_decoders
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d decoders,shared -p test -n no_decoders
 
       - name: Build without threads
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d threads,shared -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d threads,shared -p build
       - name: Test without threads
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d threads,shared -p test -n no_threads
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d threads,shared -p test -n no_threads
 
       - name: Build without BCJ filters
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d bcj,shared,nls -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d bcj,shared,nls -p build
       - name: Test without BCJ filters
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d bcj,shared,nls -p test -n no_bcj
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d bcj,shared,nls -p test -n no_bcj
 
       - name: Build without Delta filters
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d delta,shared,nls -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d delta,shared,nls -p build
       - name: Test without Delta filters
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d delta,shared,nls -p test -n no_delta
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d delta,shared,nls -p test -n no_delta
 
       - name: Build without sha256 check
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -c crc32,crc64 -d shared,nls -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -c crc32,crc64 -d shared,nls -p build
       - name: Test without sha256 check
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -c crc32,crc64 -d shared,nls -p test -n no_sha256
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -c crc32,crc64 -d shared,nls -p test -n no_sha256
 
       - name: Build without crc64 check
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -c crc32,sha256 -d shared,nls -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -c crc32,sha256 -d shared,nls -p build
       - name: Test without crc64 check
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -c crc32,sha256 -d shared,nls -p test -n no_crc64
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -c crc32,sha256 -d shared,nls -p test -n no_crc64
 
       - name: Build small
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d small -p build
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d small -p build
       - name: Test small
-        run: ./build-aux/ci_build.sh -b ${{ matrix.build_system }} -d small -p test -n small
+        run: ./build-aux/ci_build.bash -b ${{ matrix.build_system }} -d small -p test -n small
 
       # Attempt to upload the test logs as artifacts if any step has failed
       - uses: actions/upload-artifact@c7d193f32edcb7bfad88892161225aeda64e9392 #v4.0.0
diff --git a/.github/workflows/windows-ci.yml b/.github/workflows/windows-ci.yml
index 7285a78f..e02e8593 100644
--- a/.github/workflows/windows-ci.yml
+++ b/.github/workflows/windows-ci.yml
@@ -87,29 +87,29 @@ jobs:
       ##################
 
       - name: Build with full features
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -p build
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -p build
       - name: Test with full features
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -p test -n full_features
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -p test -n full_features
 
       - name: Build without threads
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -d threads,shared -p build
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -d threads,shared -p build
       - name: Test without threads
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -d threads,shared -p test -n no_threads
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -d threads,shared -p test -n no_threads
 
       - name: Build without encoders
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -d encoders,shared -p build
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -d encoders,shared -p build
       - name: Test without encoders
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -d encoders,shared -p test -n no_encoders
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -d encoders,shared -p test -n no_encoders
 
       - name: Build without decoders
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -d decoders,shared -p build
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -d decoders,shared -p build
       - name: Test without decoders
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -d decoders,shared -p test -n no_decoders
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -d decoders,shared -p test -n no_decoders
 
       - name: Build with only crc32 check
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -c crc32 -d shared,nls -p build
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -c crc32 -d shared,nls -p build
       - name: Test with only crc32 check
-        run: ./build-aux/ci_build.sh -a "--no-po4a" -b ${{ matrix.build_system }} -c crc32 -d shared,nls -p test -n crc32_only
+        run: ./build-aux/ci_build.bash -a "--no-po4a" -b ${{ matrix.build_system }} -c crc32 -d shared,nls -p test -n crc32_only
 
 
       ###############
diff --git a/build-aux/ci_build.sh b/build-aux/ci_build.bash
similarity index 100%
rename from build-aux/ci_build.sh
rename to build-aux/ci_build.bash