diff --git a/.github/workflows/e2e-tests.yml b/.github/workflows/e2e-tests.yml
index fac692020a..5ac3e6aea8 100644
--- a/.github/workflows/e2e-tests.yml
+++ b/.github/workflows/e2e-tests.yml
@@ -886,6 +886,31 @@ jobs:
                 echo "FAIL: tmp was created by a worker, meaning sys_temp_dir='tmp~1' was incorrectly evaluated to 'tmp'"
                 exit 1
               fi
+          - script: |
+              # A glibc system can carry a musl loader without being a musl system:
+              # musl-tools, a musl cross-compilation sysroot, or anything else built
+              # against musl installs /lib/ld-musl-<arch>.so.1 as well. PHPStan must
+              # still pick the glibc turbo build there - picking the musl one makes
+              # PHP refuse to load the extension at startup: "Unable to load dynamic
+              # library '.../linux-musl-x86_64/phpstan_turbo-8.5.so'
+              # (libc.musl-x86_64.so.1: cannot open shared object file)".
+              sudo touch /lib/ld-musl-x86_64.so.1
+              OUTPUT=$(bin/phpstan diagnose -l 0 -c tests/e2e/data/empty.neon)
+              echo "$OUTPUT"
+              e2e/bashunit -a contains 'Turbo platform: linux-gnu-' "$OUTPUT"
+          - script: |
+              # The mirror image of the leg above: an actual musl system must keep
+              # picking the musl build - both on Alpine, and (since /etc/alpine-release
+              # is not what makes a system musl) with that file taken away. The images
+              # ship no php.ini, so memory_limit would default to 128M, which building
+              # the DI container already exceeds.
+              DIAGNOSE='php -d memory_limit=-1 bin/phpstan diagnose -l 0 -c tests/e2e/data/empty.neon'
+              OUTPUT=$(docker run --rm -v "$PWD:/repo" -w /repo php:8.2-cli-alpine sh -c "$DIAGNOSE")
+              echo "$OUTPUT"
+              e2e/bashunit -a contains 'Turbo platform: linux-musl-' "$OUTPUT"
+              OUTPUT=$(docker run --rm -v "$PWD:/repo" -w /repo php:8.2-cli-alpine sh -c "rm /etc/alpine-release && $DIAGNOSE")
+              echo "$OUTPUT"
+              e2e/bashunit -a contains 'Turbo platform: linux-musl-' "$OUTPUT"
 
     steps:
       - name: Harden the runner (Audit all outbound calls)