diff --git a/.github/cosmo/build b/.github/cosmo/build
new file mode 100644
index 00000000..0c7f010b
--- /dev/null
+++ b/.github/cosmo/build
@@ -0,0 +1,38 @@
+#!/bin/sh
+set -eux
+
+COSMO_DIR="/sc/cosmocc"
+
+# build x86_64
+X86_64_CC="/sc/cosmocc/bin/x86_64-unknown-cosmo-cc"
+X86_64_AR="/sc/cosmocc/bin/x86_64-unknown-cosmo-ar"
+mkdir -p /sc/cosmocc/x86_64
+make -j CC="$X86_64_CC" AR="$X86_64_AR" HAS_SHARED=0 JANET_NO_AMALG=1
+cp build/janet /sc/cosmocc/x86_64/janet
+make clean
+
+# build aarch64
+AARCH64_CC="/sc/cosmocc/bin/aarch64-unknown-cosmo-cc"
+AARCH64_AR="/sc/cosmocc/bin/aarch64-unknown-cosmo-ar"
+mkdir -p /sc/cosmocc/aarch64
+make -j CC="$AARCH64_CC" AR="$AARCH64_AR" HAS_SHARED=0 JANET_NO_AMALG=1
+cp build/janet /sc/cosmocc/aarch64/janet
+make clean
+
+# fat binary
+apefat () {
+    OUTPUT="$1"
+    OLDNAME_X86_64="$(basename -- "$2")"
+    OLDNAME_AARCH64="$(basename -- "$3")"
+    TARG_FOLD="$(dirname "$OUTPUT")"
+    "$COSMO_DIR/bin/apelink" -l "$COSMO_DIR/bin/ape-x86_64.elf" \
+        -l "$COSMO_DIR/bin/ape-aarch64.elf" \
+        -M "$COSMO_DIR/bin/ape-m1.c" \
+        -o "$OUTPUT" \
+        "$2" \
+        "$3"
+    cp "$2" "$TARG_FOLD/$OLDNAME_X86_64.x86_64"
+    cp "$3" "$TARG_FOLD/$OLDNAME_AARCH64.aarch64"
+}
+
+apefat /sc/cosmocc/janet.com /sc/cosmocc/x86_64/janet /sc/cosmocc/aarch64/janet
diff --git a/.github/cosmo/setup b/.github/cosmo/setup
new file mode 100644
index 00000000..9de92d41
--- /dev/null
+++ b/.github/cosmo/setup
@@ -0,0 +1,21 @@
+#!/bin/sh
+set -e
+
+sudo apt update
+sudo apt-get install -y ca-certificates libssl-dev\
+    qemu qemu-utils qemu-user-static\
+    texinfo groff\
+    cmake ninja-build bison zip\
+    pkg-config build-essential autoconf re2c
+
+# download cosmocc
+cd /sc
+wget https://github.com/jart/cosmopolitan/releases/download/3.3.3/cosmocc-3.3.3.zip
+mkdir -p cosmocc
+cd cosmocc
+unzip ../cosmocc-3.3.3.zip
+
+# register
+cd /sc/cosmocc
+sudo cp ./bin/ape-x86_64.elf /usr/bin/ape
+sudo sh -c "echo ':APE:M::MZqFpD::/usr/bin/ape:' >/proc/sys/fs/binfmt_misc/register"
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index e5c557dc..4c19750b 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -60,3 +60,30 @@ jobs:
             ./dist/*.zip
             ./*.zip
             ./*.msi
+
+  release-cosmo:
+    permissions:
+      contents: write  # for softprops/action-gh-release to create GitHub release
+    name: Build release binaries for Cosmo
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout the repository
+        uses: actions/checkout@master
+      - name: create build folder
+        run: |
+          sudo mkdir -p /sc
+          sudo chmod -R 0777 /sc
+      - name: setup Cosmopolitan Libc
+        run: bash ./.github/cosmo/setup
+      - name: Set the version
+        run: echo "version=${GITHUB_REF/refs\/tags\//}" >> $GITHUB_ENV
+      - name: Set the platform
+        run: echo "platform=cosmo" >> $GITHUB_ENV
+      - name: build Janet APE binary
+        run: bash ./.github/cosmo/build
+      - name: push binary to github
+        uses: softprops/action-gh-release@v1
+        with:
+          draft: true
+          files: |
+            /sc/cosmocc/janet.com