diff --git a/.github/workflows/build-engines.yml b/.github/workflows/build-engines.yml
index 9ebdd1fba..bd8b39bff 100644
--- a/.github/workflows/build-engines.yml
+++ b/.github/workflows/build-engines.yml
@@ -104,8 +104,8 @@ jobs:
       fail-fast: false
       matrix:
         target:
-          - { os: ubuntu-24.04,     platform: linux-x64 }
-          - { os: ubuntu-24.04-arm, platform: linux-arm64 }
+          - { os: ubuntu-24.04,     platform: linux-x64,   manylinux: quay.io/pypa/manylinux_2_28_x86_64 }
+          - { os: ubuntu-24.04-arm, platform: linux-arm64, manylinux: quay.io/pypa/manylinux_2_28_aarch64 }
           - { os: windows-2025,     platform: win32-x64 }
     runs-on: ${{ matrix.target.os }}
     steps:
@@ -119,10 +119,19 @@ jobs:
           path: engines
           key: engines-${{ matrix.target.platform }}-${{ needs.generate.outputs.flags }}-${{ needs.generate.outputs.key }}
           restore-keys: engines-${{ matrix.target.platform }}-${{ needs.generate.outputs.flags }}-
-      - name: Compile every language (Linux)
+      # THE GLIBC FLOOR. A binary links against the glibc of the machine that built it, and runs only where that
+      # glibc or a newer one is installed. Built on ubuntu-24.04 (glibc 2.39) every engine needed GLIBC_2.38, so it
+      # would not start on Ubuntu 22.04, Debian 12, RHEL 9 or Amazon Linux 2023: the official python and node
+      # Docker images, most CI and most servers. The compile therefore runs inside manylinux_2_28 (glibc 2.28,
+      # the floor Python wheels use), and the step after it fails the build if any binary asks for more.
+      - name: Compile every language (Linux, manylinux_2_28)
         if: startsWith(matrix.target.platform, 'linux')
+        env:
+          MANYLINUX: ${{ matrix.target.manylinux }}
         run: |
           set -e
+          docker run --rm -v "$PWD:/w" -w /w -e LANGUAGES="$LANGUAGES" -u "$(id -u):$(id -g)" "$MANYLINUX" bash -ec '
+          c++ --version | head -1; ldd --version | head -1
           for lang in $LANGUAGES; do
             if cmp -s "gen/$lang.id" "engines/$lang/ENGINE_ID"; then echo "$lang: cached, rules unchanged"; continue; fi
             mkdir -p "engines/$lang"
@@ -136,7 +145,19 @@ jobs:
             c++ -std=c++17 -O3 -w -static-libstdc++ -static-libgcc -I gen "$cpp" -o "engines/queries/axiomcode-query-$q"
             cp "gen/queries/$q.id" "engines/queries/$q.id"
           done
+          '
           ls -la engines/*; ldd engines/java/axiomcode-engine-java || true
+      - name: Linux binaries need no glibc newer than 2.28
+        if: startsWith(matrix.target.platform, 'linux')
+        run: |
+          set -e
+          bad=0
+          for f in engines/*/axiomcode-*; do
+            need="$(objdump -T "$f" | grep -o 'GLIBC_[0-9.]*' | sed 's/GLIBC_//' | sort -V | tail -1)"
+            echo "$f needs glibc $need"
+            if [ "$(printf '%s\n2.28\n' "$need" | sort -V | tail -1)" != 2.28 ]; then echo "::error::$f needs glibc $need (> 2.28)"; bad=1; fi
+          done
+          exit $bad
       - uses: ilammy/msvc-dev-cmd@v1
         if: startsWith(matrix.target.platform, 'win32')
         with: { arch: x64 }