diff --git a/docker/build.sh b/docker/build.sh
index 9704e22b..e9263cb9 100755
--- a/docker/build.sh
+++ b/docker/build.sh
@@ -7,21 +7,6 @@ set -euxo pipefail
 cd $(dirname "${BASH_SOURCE[0]}")
 cd $(git rev-parse --show-toplevel)
 
-# nix-store is way quicker at copying these files and only needs to do it once
-# if the source doesn't change
-if whereis nix-store >/dev/null; then
-    SRCDIR="$(nix-store --add $PWD)"
-else
-    SRCDIR="$(mktemp -d /tmp/isle-src.XXXXXX)"
-    git ls-files -z | xargs -0I{} install -D {} "$SRCDIR/{}"
-fi
-
-cleanup () {
-    rm -rf "$SRCDIR" 2>/dev/null
-}
-
-trap cleanup EXIT
-
 declare OCI_CMD
 
 if [ "x${OCI_CMD:-}" = "x" ]; then
@@ -35,6 +20,29 @@ if [ "x${OCI_CMD:-}" = "x" ]; then
     fi
 fi
 
+# on docker, --tmpfs doesn't work correctly with the old MSVC
+if [ "$OCI_CMD" = "docker" ]; then
+    BUILDDIR="$(mktemp -d /tmp/isle-build.XXXXXX)"
+fi
+
+# nix-store is way quicker at copying these files and only needs to do it once
+# if the source doesn't change
+if whereis nix-store >/dev/null; then
+    SRCDIR="$(nix-store --add $PWD)"
+else
+    SRCDIR="$(mktemp -d /tmp/isle-src.XXXXXX)"
+    git ls-files -z | xargs -0I{} install -D {} "$SRCDIR/{}"
+fi
+
+cleanup () {
+    if ! [ "x${BUILDDIR:-}" = "x" ]; then
+        rm -rf "$BUILDDIR" 2>/dev/null
+    fi
+    rm -rf "$SRCDIR" 2>/dev/null
+}
+
+trap cleanup EXIT
+
 "$OCI_CMD" build -t isle "$SRCDIR/docker"
 
 mkdir -p result
@@ -44,11 +52,17 @@ if [[ "x${JOBS:-}" == "x" ]]; then
     JOBS=$(nproc)
 fi
 
+if ! [ "x${BUILDDIR:-}" = "x" ]; then
+    MOUNT_BUILDDIR=(-v "$BUILDDIR":/build)
+else
+    MOUNT_BUILDDIR=(--tmpfs /build)
+fi
+
 "$OCI_CMD" run -it \
     -e CMAKE_FLAGS="-DCMAKE_BUILD_TYPE=RelWithDebInfo" \
-    -v "$SRCDIR":/isle:rw \
-    -e JOBS="$JOBS" \
-    --tmpfs /build \
+    ${MOUNT_BUILDDIR[@]} \
+    -v "$SRCDIR":/isle \
     -v ./result:/install \
+    -e JOBS="$JOBS" \
     isle