diff --git a/build.sh b/build.sh
index f6bef59..2cbaced 100755
--- a/build.sh
+++ b/build.sh
@@ -20,7 +20,9 @@ function package() {
     rm "$file.zip" > 2&>/dev/null || true
     # note: would use printf "@ $(basename $file)\n@=bootstrap" | zipnote -w "$file.zip"
     # if not for https://bugs.launchpad.net/ubuntu/+source/zip/+bug/519611
-    mv "$file" bootstrap
+    if [ "$file" != ./bootstrap ] && [ "$file" != bootstrap ]; then
+        mv "${file}" bootstrap
+    fi
     zip "$file.zip" bootstrap
     rm bootstrap
 }
@@ -28,7 +30,8 @@ function package() {
 cd "$CARGO_TARGET_DIR"/release
 (
     if [ -z "$BIN" ]; then
-        find -maxdepth 1 -executable -type f -exec package {} \;
+        export -f package
+        find -maxdepth 1 -executable -type f -exec bash -c 'package "$0"' {} \;
     else
         package "$BIN"
     fi
diff --git a/tests/test-func/Cargo.toml b/tests/test-func/Cargo.toml
index 77565d3..0e94a58 100644
--- a/tests/test-func/Cargo.toml
+++ b/tests/test-func/Cargo.toml
@@ -4,6 +4,12 @@ version = "0.1.0"
 authors = ["softprops <d.tangren@gmail.com>"]
 edition = "2018"
 
+# users don't have to do this
+# but when they do, the builder packaging still work
+[[bin]]
+name = "bootstrap"
+path = "src/main.rs"
+
 [dependencies]
 lambda_runtime = "0.1"
 serde_json = "1.0"
\ No newline at end of file
diff --git a/tests/test.sh b/tests/test.sh
index 57e581a..f2a705e 100755
--- a/tests/test.sh
+++ b/tests/test.sh
@@ -46,29 +46,31 @@ DIST=$(cd $HERE/..; echo $PWD)
 
 cd ${HERE}/test-func
 
+# test packaing with a single binary
 function package_bin() {
-    rm target/lambda/release/ > /dev/null 2>&1
+    rm -rf target/lambda/release > /dev/null 2>&1
     docker run --rm \
-    -e BIN=test-func \
+    -e BIN="$1" \
     -v ${PWD}:/code \
     -v ${HOME}/.cargo/registry:/root/.cargo/registry \
     -v ${HOME}/.cargo/git:/root/.cargo/git \
     softprops/lambda-rust && \
-    ls target/lambda/release/test-func.zip > /dev/null 2>&1
+    ls target/lambda/release/bootstrap.zip > /dev/null 2>&1
 }
 
+# test packaging all binaries
 function package_all() {
-    rm target/lambda/release/ > /dev/null 2>&1
+    rm -rf target/lambda/release > /dev/null 2>&1
     docker run --rm \
     -v ${PWD}:/code \
     -v ${HOME}/.cargo/registry:/root/.cargo/registry \
     -v ${HOME}/.cargo/git:/root/.cargo/git \
     softprops/lambda-rust && \
-    ls target/lambda/release/test-func.zip > /dev/null 2>&1
+    ls target/lambda/release/bootstrap.zip > /dev/null 2>&1
 }
 
 # package tests
-assert_success "it packages single bin" package_bin
+assert_success "it packages single bin" package_bin bootstrap
 
 assert_success "it packages all bins" package_all
 
@@ -76,7 +78,7 @@ assert_success "it packages all bins" package_all
 rm test-out.log > /dev/null 2>&1
 rm -rf /tmp/lambda > /dev/null 2>&1
 unzip -o  \
-    target/lambda/release/test-func.zip \
+    target/lambda/release/bootstrap.zip \
     -d /tmp/lambda > /dev/null 2>&1 && \
   docker run \
     -i -e DOCKER_LAMBDA_USE_STDIN=1 \